Patent Description:
A rocket engine is usually mounted to a primary structure of a rocket by a Cardan suspension, such as one or more gimbals combined with another and having differently oriented axes of rotation. This allows movement of the rocket engine, for example, for controlling the thrust acting on the rocket, and, hence steering the rocket. The deflection of the rocket engine is usually not more than a few degrees.

Usually, such mounting structure of a rocket engine requires at least four ball bearings, two for each axis of rotation of the Cardan suspension, around which the rocket engine can pivot. Thus, the mounting structure of a rocket engine is quite complex.

Furthermore, <CIT> relates to a swivel mount structure for a rocket engine having a spherical support member that is placed between a coaxial annular flange extending from a closed end of the rocket casing and an annular bearing member on the side of the support member remote from the rocket casing. A space between the rocket casing and the spherical support member is sealed by seals and pressurized with a fuel component of the rocket. A channel formed by the annular bearing member is also sealed against the support member with seals and is pressurized with nitrogen.

It is an object of the present invention to provide a mounting assembly and a rocket of less complexity.

This object is solved by a mounting assembly with the features of claim <NUM> and a rocket with the features of claim <NUM>.

According to a first aspect to better understand the present disclosure, a mounting assembly for a rocket engine comprises a spherical bearing base, and a spherical retaining ring coupled with the spherical bearing base and forming a space between at least a portion of the spherical retaining ring and at least a portion of the spherical bearing base. The mounting assembly further comprises a suspension link having a spherical end, wherein the spherical end is arranged in the space between the spherical bearing base and the spherical retaining ring. The spherical bearing base is in contact with the spherical end of the suspension link via a first plurality of balls, and the spherical end of the suspension link is in contact with the spherical retaining ring via a second plurality of balls.

A component mentioned to be "spherical" means that this component comprises at least a portion having the shape of a sector of a sphere. Spherical components of the mounting assembly arranged relative to and interacting with one another are concentric and may share a common radius. For instance, the spherical end of the suspension link may be arranged with respect to the spherical bearing base, so that both components are in contact with one another over substantially the entire area of the spherical end of the suspension link or a distance between both components is substantially the same over substantially the entire area of the spherical end of the suspension link. Likewise, the spherical end of the suspension link may have a contacting area which contacts the spherical retaining ring or may have a distance to the spherical retaining ring that is substantially the same over substantially the entire area of the spherical end of the suspension link overlapping with the spherical retaining ring.

Such mounting assembly allows movement of the suspension link in at least two degrees of freedom like a Cardan suspension link. However, there is no requirement for ball bearings of such Cardan suspension. This reduces complexity of the mounting assembly. In addition, due to the areal contact between spherical bearing base, spherical retaining ring and spherical end of the suspension link, the thrust generated by the rocket engine can be transferred better into the primary structure of the rocket. For instance, the suspension link may be part of the primary structure of the rocket, such as a part of the thrust cone at a bottom portion of the rocket.

In conventional mounting structures for a rocket engine, the force induced by the thrust is transferred via ball bearings (e.g. of a Cardan suspension), which means that the entire force is transferred via a few balls of each ball bearing, such as two balls. Therefore, the ball bearings (of a Cardan suspension) were designed and dimensioned to withstand such high forces, which led to a heavy and bulky mounting structure for the rocket engine.

The disclosed mounting assembly, on the other hand, reduces complexity, weight, and size of the mounting structure between rocket engine and primary structure of the rocket, while it further allows greater forces to be transferred compared to conventional ball bearings.

Moreover, the spherical bearing base of the mounting assembly can be part of an injector head of the rocket engine or can be part of a tank for storing fuel for the rocket engine. Usually these components of a rocket are round shaped or spherical, so that they can be utilised as the spherical bearing base. This allows further reduction of the size of the mounting structure. Optionally, the respective part of the injector head or tank may be strengthened, for example, by stronger or thicker material at least for the portion forming the spherical bearing base. Even including this strengthening of the injector head or tank the entire size of the mounting assembly is still reduced compared to conventional mounting structures.

In an implementation variant, the part of the injector head forming the spherical bearing base can be a dome-shaped spherical end of the injector head facing away from a nozzle of the rocket engine. The end of the injector head facing away from a nozzle of the rocket engine is usually the top part of a combustion chamber and, hence, the top part of the rocket engine. In order to withstand the high pressure generated in the combustion chamber, this end of the injector head is often dome-shaped. Thus, a portion of the injector head can be integrated into the mounting assembly. This avoids any additional height (size) due to a mounting structure and reduces complexity. The end of the injector head may not even be redesigned, since it is constructed to withstand high forces. Optionally, the surface forming the spherical bearing base may be optimised for the sliding/gliding movement of the suspension link.

In another implementation variant, the suspension link can further comprise a strut connected to the spherical end. For instance, the strut may extend from a side of the spherical end opposite the spherical bearing base. The strut and/or the spherical end of the suspension link may be axially symmetric.

Furthermore, the spherical retaining ring can comprise an opening, wherein the strut of the suspension link reaches through the opening. In other words, the spherical retaining ring covers at least a portion of the spherical end of the suspension link and surrounds the strut.

In an implementation variant, an outer diameter of the strut can be smaller than an inner diameter of the opening in the spherical retaining ring. This allows movement of the suspension link with respect to the spherical retaining ring. This movement is limited by the inner diameter (inner edge) of the opening in the spherical retaining ring.

In a further implementation variant, at least one of the contacting surfaces of the spherical bearing base, the spherical retaining ring and the suspension link contacting one another contains and/or is coated with polytetrafluoroethylene (PTFE). For example, the spherical end of the suspension link may have a contacting surface contacting a corresponding surface of the spherical bearing base. Likewise, the spherical end of the suspension link may have a contacting surface contacting a corresponding surface of the spherical retaining ring. Preferably, the contacting surfaces of the spherical end of the suspension link are arranged concentrically to one another and on opposite sides of the suspension link. At least one of these contacting surfaces may be modified to facilitate gliding of the other component gliding thereon. Such modification may comprise a coating reducing frictional forces, one exemplary coating is PTFE.

In yet another implementation variant, the number of the first plurality of balls is preferably greater than two, in order to provide a sufficient amount of transfer points for the forces induced by the thrust of the rocket engine to be transferred between the spherical bearing base and the spherical end of the suspension link. Due to the concentric form of the spherical bearing base and the spherical end of the suspension link, each ball of the first plurality of balls contacts the spherical bearing base as well as the spherical end of the suspension link, and, hence, improves the transfer of forces. Thus, a diameter of each ball the first plurality of balls is the same.

Optionally, the first plurality of balls can be secured in a spherical cage. While the simplest implementation of such cage is a ring holding the outermost balls, the cage may have a spherical shape and a support for at least some of the first plurality of balls. Therefore, a distance between adjacent balls can be predefined and set by the supports in the cage, which allows a uniform distribution of force and transfer points between spherical bearing base and suspension link.

In another implementation variant, as with the first plurality of balls, the number of balls of the second plurality of balls may be greater than two for an improved transfer of forces between the suspension link and the spherical retaining ring.

Also optionally, the second plurality of balls can be secured in a spherical ring cage. The simplest form of such ring cage is an inner ring securing the second plurality of balls from falling through the opening in the spherical retaining ring. On the other hand, the cage may have a spherical ring shape, i.e. has the form of a section of a sphere including an opening in the section. Thus, the spherical ring cage can be threaded onto (loosely laid around) the strut of the suspension link before the spherical retaining ring is threaded onto (loosely laid around) the strut.

In yet another implementation variant, the spherical retaining ring can comprise a sidewall disposed around a circumferential outer edge of the spherical end of the suspension link and limiting a movement of the suspension link in the space between the spherical bearing base and the spherical retaining ring. In other words, the sidewall of the spherical retaining ring extends from a concentric part of the spherical retaining ring towards the spherical bearing base and thereby delimits at least a portion of the space between the spherical bearing base and the spherical retaining ring.

In a further implementation variant, an outer diameter of the circumferential outer edge of the spherical end of the suspension link is smaller than an inner diameter of the sidewall of the spherical retaining ring. The difference between both diameters defines the possible moving distance of the spherical end of the suspension link within the space defined by the spherical retaining ring, its sidewall and the spherical bearing base, and hence a deflection of the strut around a common centre of the spherical components of the mounting assembly.

According to a second aspect to better understand the present disclosure, a rocket can comprise a rocket engine, a fuel tank, and at least one mounting assembly according to the first aspect or one of its variants for mounting the rocket engine.

For instance, a part of the fuel tank and/or a part of the rocket engine forms the spherical bearing base of one of the mounting assemblies.

The present disclosure is not restricted to the aspects and variants in the described form and order. Specifically, the description of aspects and implementation variants is not to be understood as a specific limiting grouping of features.

Preferred embodiments of the invention are now explained in greater detail with reference to the enclosed schematic drawings, in which.

<FIG> schematically illustrates a cross-section of a mounting assembly <NUM> for mounting a rocket engine <NUM>, and <FIG> schematically illustrates a perspective view of the mounting assembly <NUM> partially cut open. The mounting assembly <NUM> includes a bearing base <NUM>. The bearing base <NUM> has a spherical shape, i.e. is part of a sphere with a centre X. The spherical bearing base <NUM> can be part of an injector head <NUM> of the rocket engine <NUM> (<FIG>). For example, an injector head <NUM> can have a dome-shaped spherical upper end <NUM>, so that it can be integrated easily into the mounting structure for mounting the rocket engine <NUM>. The upper end <NUM> of the injector head <NUM> is disposed opposite to a nozzle <NUM> of the rocket engine <NUM>.

Alternatively, the spherical bearing base <NUM> can be part of a tank <NUM> for storing fuel for the rocket engine <NUM> (<FIG>). The shape of such fuel tank <NUM> for a rocket <NUM> is often a sphere or has at least a spherical portion, in order to withstand the high pressure of the fuel stored in the tank <NUM> and in order to minimize the surface of the tank <NUM> for reduced heat losses. Thus, such a portion of the tank <NUM> can be integrated easily into the mounting structure for mounting the rocket engine <NUM>, for example by forming the spherical bearing base <NUM> of the mounting assembly <NUM>. The mounting assembly <NUM> further comprises a spherical retaining ring <NUM> coupled with the spherical bearing base <NUM>. For instance, the spherical retaining ring <NUM> can be mounted to the spherical bearing base <NUM> by a plurality of fasteners <NUM>. Such fasteners <NUM> may couple a flange portion <NUM> of the retaining ring <NUM> with a corresponding flange portion <NUM> of the bearing base <NUM>. Alternatively or additionally, the retaining ring <NUM> may be welded to the bearing base <NUM>.

The spherical retaining ring <NUM> is shaped, so that it forms a space between at least a portion of the spherical retaining ring <NUM> and at least a portion of the spherical bearing base <NUM>. The retaining ring <NUM> and the bearing base <NUM> are each sections of a respective sphere sharing a common centre X, i.e. are concentric. The spherical retaining ring <NUM> may comprise a sidewall <NUM> disposed around the space between the retaining ring <NUM> and the bearing base <NUM>. For instance, the sidewall <NUM> may connect the spherical part with the flange portion <NUM> of the retaining ring <NUM>.

Inside this space between the retaining ring <NUM> and the bearing base <NUM> is a spherical end <NUM> of a suspension link <NUM>. The spherical end <NUM> of the suspension link <NUM> has a thickness (in a radial direction), which is preferably constant and is equal to or smaller than a thickness (in the radial direction) of the space between the spherical retaining ring <NUM> and the spherical bearing base <NUM>. In addition, a circumferential outer edge <NUM> of the spherical end <NUM> of the suspension link <NUM> may be dimensioned, in order to be spaced apart from the sidewall <NUM> of the retaining ring <NUM>. Thus, the sidewall <NUM> limits the movement of the suspension link <NUM>.

While the spherical end <NUM> could glide on a surface of the bearing base <NUM> as well as on a surface of the retaining ring <NUM>, a plurality of balls are arranged between the spherical end <NUM> and the bearing base <NUM> as well as between the spherical end <NUM> and the retaining ring <NUM>. For instance, a first plurality of balls <NUM> is arranged between the bearing base <NUM> and the suspension link <NUM>, and a second plurality of balls <NUM> is arranged between the suspension link <NUM> and the retaining ring <NUM>. Each of the plurality of balls <NUM>, <NUM> can optionally be secured in a spherical cage <NUM> and spherical ring cage <NUM>, respectively, which are best illustrated in <FIG>.

The retaining ring <NUM> can comprise an opening <NUM>, and the suspension link <NUM> can comprise a strut <NUM> reaching through the opening <NUM>. In order to allow the suspension link <NUM> to move inside the space between the bearing base <NUM> and the retaining ring <NUM>, an outer diameter of the strut <NUM> is smaller than an inner diameter of the opening <NUM> in the spherical retaining ring <NUM>. As illustrated in <FIG>, the suspension link <NUM> can move around the centre X by a certain degree (-X° to +X°), for example, the suspension link <NUM> can deflect from a normal N by up to approximately <NUM>°, preferably by up to approximately <NUM>° and more preferably, by up to approximately <NUM>°. This movement is limited by the inner diameter of the opening <NUM> and/or the inner diameter of the sidewall <NUM> of the retaining ring <NUM>. Of course, the movement of the suspension link <NUM> is also limited by an outer diameter of the strut <NUM> in relation to the inner diameter of the opening <NUM> and/or an outer diameter of the circumferential outer edge <NUM> of the spherical end <NUM> of the suspension link <NUM> in relation to the inner diameter of the sidewall <NUM>.

While <FIG> illustrates a movement of the strut <NUM> of the suspension link <NUM> relative to the bearing base <NUM> and retaining ring <NUM>, it is to be understood that the strut <NUM> may be fixedly connected with the primary structure of the rocket <NUM>, so that the bearing base <NUM> and retaining ring <NUM> move relative to the suspension link <NUM>. In other words, while the suspension link <NUM> is fixed with respect to the rocket <NUM>, the rocket engine <NUM> can be moved around the centre X by the above amount -X° to +X°.

<FIG> illustrates schematically a portion of a cross-section of a rocket <NUM>. Particularly, <FIG> illustrates a bottom portion of the rocket <NUM> including a tank <NUM> and a rocket engine <NUM>. The rocket engine <NUM> comprises a nozzle <NUM> and an injector head <NUM>, which usually includes a combustion chamber. The fuel burned in the combustion chamber exits through the nozzle <NUM> and generates thrust in an upward direction in <FIG>. This thrust is transferred via a mounting assembly <NUM> to the remaining portion of the rocket <NUM>, for example, into a primary structure (not illustrated) of the rocket <NUM>.

While <FIG> illustrates the mounting assembly <NUM> as having a spherical bearing base <NUM> integrated into the dome-shaped end <NUM> of the injector head <NUM>, the spherical bearing base <NUM> can alternatively be integrated into a portion of the tank <NUM>.

Claim 1:
A mounting assembly (<NUM>) for a rocket engine (<NUM>), the mounting assembly (<NUM>) comprising:
- a spherical bearing base (<NUM>);
- a spherical retaining ring (<NUM>) coupled with the spherical bearing base (<NUM>) and forming a space between at least a portion of the spherical retaining ring (<NUM>) and at least a portion of the spherical bearing base (<NUM>);
- a suspension link (<NUM>) having a spherical end (<NUM>), wherein the spherical end (<NUM>) is arranged in the space between the spherical bearing base (<NUM>) and the spherical retaining ring (<NUM>);
- a first plurality of balls (<NUM>) arranged between the spherical bearing base (<NUM>) and the spherical end (<NUM>) of the suspension link (<NUM>); and
- a second plurality of balls (<NUM>) arranged between the spherical end (<NUM>) of the suspension link (<NUM>) and the spherical retaining ring (<NUM>),
wherein the spherical bearing base (<NUM>) is in contact with the spherical end (<NUM>) of the suspension link (<NUM>) via the first plurality of balls and the spherical end (<NUM>) of the suspension link (<NUM>) is in contact with the spherical retaining ring via the second plurality of balls (<NUM>), and
wherein the spherical bearing base (<NUM>) is part of an injector head (<NUM>) of the rocket engine (<NUM>) or is part of a tank (<NUM>) for storing fuel for the rocket engine (<NUM>).