Patent Description:
Furthermore, the invention relates to a hydraulic gerotor or geroler machine comprising such a check valve.

Such a check valve is known, for example, from <CIT>. The valve element is in form of a ball which is guided between ducts, wherein the ducts connect the valve chamber to the second port.

Further valves are known from <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

A check valve is used to allow a flow of a fluid in one direction and to block the flow of the fluid in the opposite direction, at least when there is a pressure gradient across the check valve. Current designs of check valves, in particular for hydraulic motors, especially gerotor/geroler motors, use many components or complicated structures, which increases the package size and adds costs. It usually increases also external leakage points.

The object underlying the invention is to have a simple check valve design.

This object is solved with a check valve described at the outset with the features of claim <NUM>.

Inter alia, the second port opens into the stop face by means of an array of holes, wherein a cross section area of the holes is smaller than the smallest cross section area of the valve element.

In such a check valve basically only three parts are necessary, namely the two parts of the valve housing and the valve element. The array of holes allow a flow of the fluid when the check valve is open. The valve element is stopped at the stop surface, however, it cannot close all of the holes of the array, so that a flow is still possible.

In an embodiment of the invention the area of the array is larger than the largest cross section of the valve element. Thus, a sufficient flow area is permanently available, so that a pressure drop in the check valve can be kept low in an open condition of the check valve.

The valve element is moveable perpendicular to the valve seat axis. In other words, the valve element is not guided within the valve chamber, but is free to move in the valve chamber.

In an embodiment of the invention the stop face is a plane face. This simplifies the machining of the second part.

In an embodiment of the invention the stop face is in form of a bowl. This simplifies assembly of the check valve, when in a mounting position the stop face is arranged at the lowest position in direction of gravity. The valve element can simply be positioned on the stop face and the first housing part can be mounted to the second housing part from the top. The form of the bowl differs from the form of the valve element, so that the valve element cannot close all of the holes at the same time.

The stop face is part of an end face of the second part. The end face of the second part is the face which contacts the first part of the valve housing. This simplifies further the design of the check valve.

In an embodiment of the invention the holes cover at least <NUM>% of the stop face. The stop face is as large as the cross section of the valve chamber. Basically, the area can cover the whole cross section of the valve chamber. However, in most cases it is sufficient when the holes cover at least <NUM>% of the stop face.

In an embodiment of the invention at least some of the holes are arranged on a circle. This again allows for a flow of fluid out of the second port independently of the exact position of the valve element. A main flow bore can be arranged at the centre of the circle. In an open condition, this main flow bore might be closed or at least partly closed by the valve element. However, at least some of the remaining holes of the array remain open.

In an embodiment of the invention the circle has a centre that coincides with the valve seat access. Accordingly, symmetric conditions can be achieved which is positive for the flow of the fluid through the check valve.

The array covers an area which is larger than a cross section of the second port. Thus, enough area is available for the array of holes.

The valve element is in form of a ball. The ball can be used, on the one hand, to close the check valve when it seats against the valve seat. On the other hand, when it rests against the stop face, there is always a space available through which the flow of fluid can escape to the second port.

In an embodiment of the invention a sealing is arranged between the first housing part and the second housing part. Such a sealing keeps the risk of a leakage low.

The invention furthermore relates to a hydraulic gerotor or geroler machine comprising such a check valve.

A hydraulic gerotor or geroler machine is an orbiting machine which is preferably used as a hydraulic motor for different functions. One function of a check valve is to prevent cavitation which may occur during pumping operation of the hydraulic motor due to inertial loading of the machine/application. Generally, in a gerotor or geroler motor which is used for swing application of an excavator, the check valve is used to connect case flow line to one of the directional ports so as to direct the drain line/case flow to the respective directional ports during pumping operation of the hydraulic motor.

In an embodiment of the invention the machine comprises a machine housing, wherein a part of the machine housing forms a part of the valve housing. This simplifies the construction of the hydraulic machine.

In an embodiment of the invention the part of the machine housing forms the first part of the valve housing. Thus, fluid is blocked from entering the hydraulic machine in this case. However, in many cases, such a hydraulic machine will comprise two such check valves, which open in opposite directions. In this case the machine housing forms the second part of the valve housing of the second check valve.

Preferred embodiments of the invention will now be described with reference to the drawings, wherein:.

<FIG> shows a check valve <NUM> comprising valve housing having a first port <NUM> and a second port <NUM>. Both ports <NUM>, <NUM> are connected to a valve chamber <NUM>. The first port <NUM> opens into the valve chamber <NUM> by means of a valve seat <NUM>. The valve seat <NUM> comprises a valve seat axis <NUM>.

A valve element <NUM> is arranged in the valve chamber <NUM>. The valve element <NUM> is in form of a ball. The valve element <NUM> is moveably arranged within the valve chamber <NUM> between the valve seat <NUM> and a stop face <NUM> opposite the valve seat <NUM>.

The valve housing comprises a first part <NUM> having the first port <NUM> and a second part <NUM> having the second port <NUM>. The second part <NUM> is connected to the first part <NUM>. Sealing means <NUM>, for example an O-ring, are arranged between the first part <NUM> and the second part <NUM>.

The second port <NUM> opens into the stop face <NUM> by means of an array of holes <NUM>. The cross section of the holes <NUM> is smaller than the smallest cross section area of the valve element <NUM>. In the embodiment described the valve element <NUM> is in form of a ball, so that the diameter of the ball defines the cross-section area of the valve element. The holes <NUM> can be in form of cylinder bores having a diameter which is smaller than the diameter of the ball shaped valve element <NUM>.

The stop face <NUM> is a plane face. Thus, when the valve element <NUM> rests against the stop face <NUM>, there is always a number of holes <NUM> open to allow a fluid to escape out of the valve chamber <NUM> to the second port <NUM>.

In another embodiment the stop face <NUM> is in form of a bowl. The bowl can be rather flat. The form of the bowl serves to facilitate assembly of the check-valve, when the stop face <NUM> is arranged below the valve element <NUM>. In the case the valve element <NUM> is simply positioned in the bowl and the first part <NUM> can be mounted to the second part <NUM> without the risk that the valve element <NUM> gets lost during assembly.

As can be seen in <FIG>, the diameter of the valve chamber <NUM> is much larger than the diameter of the valve element <NUM>. Accordingly, the valve element <NUM> is not only moveable between the valve seat <NUM> and the stop face <NUM>, but it can also move perpendicular to the valve seat axis <NUM>. In other words, the valve element <NUM> is not guided in the valve chamber <NUM>.

According to the invention, the stop face <NUM> is an end face of the second part <NUM>.

This means that the stop face <NUM> forms a part of the end face of the second part <NUM>. This end face contacts the first part <NUM>, when the two parts <NUM>, <NUM> are connected to each other. The holes are machined into this stop face <NUM>, for example by drilling.

The holes <NUM> cover at least <NUM>% of the stop face. This takes into account, that a circular hole leaves material around it. Even when the whole cross section of the valve chamber <NUM> would be covered by holes <NUM>, there would be not all of the cross section available for a fluid flow.

At least some of the holes <NUM> are arranged on a circle, as can be seen in <FIG>. The circle has a centre that coincides with the valve seat access. Thus, the check valve <NUM> has a rotational symmetry. A main flow hole (not shown) can be arranged at the centre.

The array in which the holes <NUM> are arranged covers an area which is larger than a cross section of the second port <NUM>. However, the holes <NUM> at least partly overlap the cross section of the port <NUM>. This again makes sure that there is always a way for the fluid to flow through the check valve <NUM>, when the check valve <NUM> is open.

<FIG> shows the check valve <NUM> in a closed condition. When the flow of fluid is directed from the second port <NUM> to the first port <NUM> the valve element <NUM> is dragged to the valve seat <NUM> and closes the check valve <NUM>.

<FIG> shows the check valve <NUM> in open condition. In this condition the flow is directed from the first port <NUM> to the second port <NUM> and the valve element <NUM> is lifted of the valve seat <NUM> and brought into a contact with the stop face <NUM>. However, as can be seen in <FIG>, there is always at least one hole <NUM> open which is connected to the second port <NUM>, so that fluid can flow out of the valve chamber <NUM>.

<FIG> shows a hydraulic gerotor or geroler machine <NUM> comprising such a check valve <NUM>. The hydraulic machine <NUM> comprises a gerotor set <NUM>. The gerotor set <NUM> comprises a star wheel <NUM> rotating and orbiting within ring gear <NUM> (when the gerotor set <NUM> comprises rollers instead of the tips of the teeths of the ring gear <NUM>, it is referred to as "geroler"). A dog bone <NUM> transfers the rotating movement to a working section, which in the present embodiment comprises a brake <NUM>.

The hydraulic machine <NUM> comprises a valve plate <NUM> on one side of the gerotor set <NUM> and a wear plate <NUM> on the opposite side of the gerotor set <NUM>.

It should be mentioned, that the machine <NUM> comprises not only one check valve <NUM> (as shown), but two check valves opening in opposite flow directions. The other check valve would only be visible at another cross-sectional view.

Such a hydraulic gerotor or geroler motor is often used in construction equipment, like excavators. Such a check valve <NUM> in hydraulic motors is used for different functions. One function of the check valve <NUM> is to prevent cavitation which may occur during pumping operation of the hydraulic motor due to inertial loading of the machine or application.

When a gerotor or geroler motor is used for swing application of the excavator the check valve <NUM> is used to connect case flow line to one of the directional ports, so as to direct the drain line to the other directional port during pumping operation of the hydraulic motor.

In the check valve <NUM> shown in <FIG> the valve plate <NUM> which is part of a machine housing of the hydraulic gerotor or geroler machine <NUM> forms the first part <NUM> of the valve housing, while the second part <NUM> of the valve housing is fixed to the valve plate <NUM>. For the other check valve (not shown) it is just the other way round, so that the valve plate <NUM> forms the second part <NUM> of the valve housing.

<FIG> shows the check valve <NUM> in an assembly condition, in which the valve chamber <NUM> opens upwardly in direction of gravity. Thus, the valve element <NUM> can be inserted into the valve chamber <NUM> before fixing the second housing part <NUM> to the first housing part <NUM>.

Each array of holes <NUM> comprises holes <NUM> arranged around a main flow hole and are connected to the second port <NUM>. The second port <NUM> of one check valve is connected to one directional port and the second port <NUM> of the other check valve is connected to the other directional port.

Claim 1:
Check valve (<NUM>) for a hydraulic Gerotor or Geroler machine, the check valve (<NUM>) comprising a valve housing having a first port (<NUM>) and a second port (<NUM>) connected to a valve chamber (<NUM>), a valve seat (<NUM>) having a valve seat axis (<NUM>) and being arranged between the first port (<NUM>) and the valve chamber (<NUM>), and a valve element (<NUM>) movably arranged within the valve chamber (<NUM>) between the valve seat (<NUM>) and a stop face (<NUM>) opposite the valve seat (<NUM>), wherein the valve housing comprises a first part (<NUM>) having the first port (<NUM>) and a second part (<NUM>) having the second port (<NUM>) and being connected to the first part (<NUM>),
wherein the second port (<NUM>) opens into the stop face (<NUM>) by means of an array of holes (<NUM>), wherein the stop face (<NUM>) is part of an end face of the second part (<NUM>), wherein the end face of the second part (<NUM>) is the face which contacts the first part (<NUM>) of the valve housing and wherein the holes are machined into the stop face (<NUM>),
wherein the valve element (<NUM>) is in form of a ball so that a diameter of the valve element (<NUM>) defines the cross section area of the valve element (<NUM>) and wherein the holes (<NUM>) are in form of cylinder bores having a diameter which is smaller than the diameter of the ball-shaped valve element (<NUM>), and
wherein the holes (<NUM>) at least partly overlap the cross section of the second port (<NUM>),
characterized in that
only three parts are necessary in the check valve (<NUM>), namely the first part (<NUM>), the second part (<NUM>), and the valve element (<NUM>), in that the array covers an area which is larger than a cross section of the second port (<NUM>), and in that the valve element (<NUM>) is not guided within the valve chamber (<NUM>) and is movable perpendicular to the valve seat axis (<NUM>).