WO2008125106A1

WO2008125106A1 - Gerotor motor

Info

Publication number: WO2008125106A1
Application number: PCT/DK2008/000128
Authority: WO
Inventors: Henning Lund Larsen
Original assignee: Sauer-Danfoss Aps
Priority date: 2007-04-12
Filing date: 2008-04-09
Publication date: 2008-10-23
Also published as: DE102007017652A1

Abstract

In a gerotor motor, deformations in the motor shaft (6) occur due to the oil pressure in the region of the rotary valve arrangement (23) controlling the inlet and outlet of hydraulic oil to the fluid chambers (19). The gaps (36) between the motor shaft (6) and housing (18) can thus be enlarged and increased leakage losses can occur. In order to avoid such an effect, the invention proposes that supporting means (10) for the recesses (12, 13, 14) of the rotary valve arrangement (23) be provided in the motor shaft (6) in the region of said recesses (12, 13, 14).

Description

Gerotormotor

The invention relates to a rotary piston machine with a toothed wheel, a toothed ring enclosing this, forming with it displacement chambers, a motor shaft and a propeller shaft rotatably connecting the gear and the motor shaft, wherein the motor shaft and a motor housing receiving the housing a rotary valve arrangement comprising recesses for controlling the Displacement chambers has. In particular, the invention relates to a gerotor motor.

Such machines are known as motors, pumps or flow meters. They are used, for example, as a drive for vehicles and machines, in hydrostatic steering units and in many other areas.

The drive or pump unit of such rotary piston machines is formed by a so-called gerotor gear set with a fixed outer toothed ring and a gear arranged therein. The inner gear has one tooth less than the outer toothed ring. As a result, a corresponding number of displacement chambers are formed between the outer sprocket and the inner sprocket. By appropriate control of these displacement chambers, the inner gear is set in motion, simultaneously rotating and orbiting within the inner gear ring.

Power transmission from the inner sprocket to the motor shaft, which is in communication with external components, is accomplished using a cardan shaft. The cardan shaft is rotatably connected to the gear, as well as with the motor shaft. During operation, the cardan shaft rotates and nutates. To make room for the Nutationsbewegung the propeller shaft create, is usually in the motor shaft, a receiving space, usually in the form of a cylindrical recess provided.

In order to fluidically connect the displacement chambers at an appropriate time with the high-pressure hydraulic supply line or with the low-pressure connection line to the hydraulic storage tank, a suitable drive device is required. Nowadays, a rotary valve arrangement which usually extends over a certain axial length of the motor shaft serves as a rule. The rotary valve arrangement typically consists of two annular channels and a number of associated axial channels, which are arranged along the outer circumference of the motor shaft. These occur during the rotation of the motor shaft in the housing with correspondingly arranged inlet and discharge lines in contact, which are arranged in the motor shaft receiving motor housing and corresponding openings, which are directed towards the motor shaft have.

Such rotary piston machines are known for example from DE 19 06 445 C1 or DE 26 06 172 C2. In the engines shown there, the receiving opening for the cardan shaft in the motor shaft is formed very deep. The receiving opening extends over a large part of the range of the motor shaft, which lies in the motor housing, away. This arrangement is generally chosen to minimize the angle between propshaft and motor shaft or propeller shaft and inner gear (Nutationswinkel). In this way, the losses and wear in the respective storage locations should be avoided as far as possible. The disadvantage here is that a large part of the motor shaft is formed only very thin due to the gimbal recess. As a result, there are inevitably large parts of the recesses formed in the motor shaft, which are part of the rotary valve arrangement, in a region in which the motor shaft has only a small wall thickness. A large part of the rotary valve recesses is therefore only thin-walled. supports. If the rotary piston machine is operated under high pressure, then this pressure also acts and in the region of the recesses of the rotary valve arrangement radially from the outside on the motor shaft. This deforms not insignificantly due to the only thin-walled design of the motor shaft 5. The deformation is sufficient to cause a noticeable increase in the gap between the motor shaft and the motor shaft receiving space in the housing. The size of the leaks increases, whereby the efficiency of the engine decreases accordingly. The object of the invention is therefore to provide a rotary piston machine with reduced leakage losses.

For this purpose, a rotary piston machine, in particular a gerotor motor, with a gear, this enclosing, 5 with him displacement chambers forming toothed ring, a motor shaft and the gear and the motor shaft rotatably connecting propeller shaft, wherein the motor shaft and the motor shaft receiving housing a recesses comprehensive rotary valve arrangement for controlling the displacement chambers, to the effect form that o the walls of the recesses are supported by at least one support means. By supporting the walls of the recesses with the aid of the support means or the support means, the deformation of individual regions of the rotary piston machine can be reduced. As a result, deformation-induced leakage losses can be avoided so that the efficiency of the rotary piston machine can be increased.

In particular, the walls of the recesses formed in the motor shaft should be supported by at least one support means. Specifically, the high-pressure recesses should be supported by a Stützmit- tel. It is quite conceivable that the (usually) high-pressure recesses at certain operating times can also be under a low pressure. A special ders low leakage results when a larger proportion or all recesses each have at least one support means. It is conceivable that different recesses have different support means. It is also possible that individual or all recesses each have a plurality of support means. Incidentally, it can also be useful if at least certain areas of the motor shaft have at least one support means. In particular, it may be the area between high pressure areas and low pressure areas of the rotary valve arrangement. This also leakage losses can be reduced again.

A possible construction results if at least one support means is designed as a material reinforcement. This can be achieved, for example, in that the thin-walled section of the cardan shaft receiving the cardan shaft is made less deep in the motor shaft. It is also conceivable to provide the corresponding section of the motor shaft with a greater material thickness, for example by providing a two or more stepped cardan recess. If you do not want to increase the outer dimensions of the rotary piston engine, if necessary, the length of the propeller shaft must be shortened accordingly. This can lead to increased eccentricity and increased wear of the joints between propshaft and motor shaft or propeller shaft and inner gear. However, this effect can be overcompensated by the lower leakage losses and the associated higher efficiency. Another advantage of a thicker wall motor shaft is that the deflection of the shaft in the case of radial loads (eg when a wheel is connected to the motor shaft) can be reduced. This can also lead to a further reduction of leaks or to a lower wear of the rolling bearing device by "skewed position" and cause a better running behavior. Another advantage of a shorter propeller shaft is that the twist angle of the propshaft under Load can be reduced, whereby the wake of the rotary valve assembly relative to the gear set can be reduced, which can also contribute to increasing the efficiency of the gerotor motor. Due to the larger wall thicknesses or the proportionately longer area of the motor shaft without cardan recess, the total mass of the rotary piston machine can increase. However, this effect can be at least partially compensated for by providing one or more bores distributed over the cross section in the corresponding region of the motor shaft, which reduce the weight without excessively reducing the stability of the corresponding region of the motor shaft.

Another possible embodiment of at least one support means is to form this as a static device. A statics device can be understood to mean any structure which, according to the laws of statics, has the effect of increasing the stability. These may be, for example, furrow-like, bead-like or web-like structures (running in the axial direction and / or radial direction) or honeycomb structures. In this context, it proves to be particularly advantageous if an already to be provided material structuring is used as a static device. For example, the non-rotatable connection between propeller shaft and motor shaft can be formed in that the corresponding end of the propeller shaft has a slightly convex shaped portion whose surface is provided with longitudinal grooves and the inside of the gimbal has correspondingly arranged longitudinal grooves. If the longitudinal grooves provided in the cardan bore of the motor shaft are arranged at least partially in the area of recesses of the rotary valve arrangement, these longitudinal grooves, which are present in any case, can serve as a static device at the same time. This can reduce the manufacturing costs accordingly. Another possible embodiment of at least one support means results when this is designed in the form of a material change. In this context, a change in material means, for example, a separate hardening process of the material (for example induction hardening). It is also conceivable that a different material or a material change in the form of a change in the alloy composition is provided in this area. As a result, the advantages of the invention can be achieved without the entire motor shaft having to be hardened cost-intensive or consisting of a corresponding material.

It is also advantageous if at least one support means extends over at least 50% of the width of the corresponding recess. Experiments have shown that even with this proportion, it is possible to achieve a significant reduction in the leakage losses and thus a noticeable improvement in the efficiency. "Width" is to be understood in particular as the extent in the axial direction. A further surprisingly significant increase in the tightness results when at least one support means extends over at least 60% of the width of the corresponding recess. Another surprisingly strong increase in the tightness results with further increasing proportion, for example when the support means extends over at least 70%, 80%, 90% and 95% of the width of the corresponding recess. The greatest effect of the invention results when at least one support means extends over the entire width of the corresponding recess. The invention can also be realized if the said overlapping areas are realized by juxtaposing different, respectively shorter, supporting means. In a corresponding manner, it can also be advantageous if at least one support means extends over at least 50%, 60%, 70%, 80%, 90% or 100% of the axial length of the part of the motor shaft located in the housing. The statements already made apply accordingly. It is advantageous if the motor shaft is supported by peripheral rolling bearing devices. Such rolling bearing devices can be arranged on only one side, in particular on the side adjacent to the drive gear, or else the side spaced therefrom. Of course, rolling bearing devices can be provided at both ends of the motor shaft. With such rolling bearing devices, the efficiency of the rotary piston machine can be increased again. The term roller bearing is interpreted broadly in this context and may in particular also include ball bearings and carb bearings.

It is also advantageous if the motor shaft has recesses, in particular a receiving space for at least partially receiving the propeller shaft. Through such recesses in the motor shaft, the total weight of the rotary piston machine can be reduced.

Serves the corresponding recess at the same time as a receiving space for the cardan shaft, so the size of the rotary piston machine can be reduced. The depth of the recess for the propeller shaft is preferably only a certain portion of the range of the motor shaft, which is located in the housing. In particular, the depth of the cardan bore in the motor shaft is less than 70% of the length of the range of the motor shaft that is in the housing. Also conceivable in this context are 90%, 80%, 60%, 50%, 40%, 30%, 20% or 10%. In addition to the cardan recess, which is provided as a receiving space for at least partially receiving the propeller shaft, also further recesses may be provided, which cause a weight reduction of the rotary piston machine by the material removal. In particular, it may be a longitudinal bore which extends along the central axis of the motor shaft. It is also possible to provide a plurality of bores arranged, for example, in a circular manner and at a distance from the center line of the motor shaft. The weight-reducing holes can of course also be provided in a region of the motor shaft. 2008/000128

8th

that which is outside the range of the motor shaft, which is arranged in the housing. All recesses - including the cardan recess for the cardan shaft - can also be designed stepped, d. H. seen in the axial direction have different cross-sections.

It is also advantageous if the non-rotatable connection between propshaft and motor shaft and / or between propshaft and gear is done by a positive connection. In particular, for the connection between propeller shaft and motor shaft, it is possible that the corresponding positive connection simultaneously acts as a static device and thus stabilizing the rotary valve assembly. As a positive connection is in particular an arrangement of mutually correspondingly formed longitudinal grooves on cardan shaft, motor shaft and / or gear into consideration, which engage positively in one another.

It is advantageous if the diameter of the cardan shaft is at least 20% of its length. As a result, relatively large forces can be transmitted. Optionally, with such a thick design of the cardan shaft, it is also possible to provide weight-reducing recesses in the interior of the cardan shaft, for example in the form of bores, without the stability of the cardan shaft suffering. In addition, with such a ratio of diameter to length, the propeller shaft can be made shorter in relation to known construction designs, so that the rotary piston machine, in which the propeller shaft is used, may have correspondingly smaller outer dimensions. Of course, other diameter / length ratios can be selected here, in particular 25%, 30%, 35%, 45% and 50%.

A further advantageous embodiment is obtained when the rotary piston machine has a preferred direction of rotation, wherein the high-pressure side recess (s) of the rotary valve arrangement at an internal rotational position. 2008/000128

ren gear spaced side of the motor shaft are formed. In this area is usually no recess, such as to provide a cardan recess for receiving the propeller shaft. If the high-pressure region of the rotary-piston machine is arranged precisely in this region, the leakage losses that occur can be correspondingly reduced. Are located in this area of the motor shaft recesses, they usually serve only the weight reduction, so that their size and shape has a wide design freedom, or such recesses can be completely eliminated. Therefore, a particularly large support of the corresponding recess, which is part of the rotary valve arrangement, possible. Leakage losses can be avoided to a special extent. The above does not exclude that the rotary piston machine can also be operated with other pressure conditions in certain operating modes. Seen over the total operating time of the rotary piston machine, however, a higher efficiency can result overall from the proposed arrangement.

Further training possibilities, advantages and objects of the invention will become apparent from the following embodiment of a gerotor motor, with reference to the accompanying drawings.

It shows:

1 shows a schematic cross section through an embodiment of a gerotor motor.

2 shows a cross section through a gear-toothed-ring drive device.

In Fig. 1, a gerotor motor 1 is shown in a schematic cross-sectional view. The gerotor motor 1 has a gerotor gear set 2 on its left side in FIG. To clarify the structure of the gerotor gear set 2, a cross-sectional view along the cross-sectional plane H-II is shown in FIG.

The gerotor gear set 2 has an outer toothed ring 3 with inner teeth 22 and an inner gear 4 with outer teeth 21 arranged therein (see Fig. 2). The inner gear 4 has a tooth 21 less, as teeth 22 are provided in the outer toothed ring 3. In this way, between the inner gear 4 and outer ring gear 3 more fluid chambers 19 formed by a suitable pressurization of the fluid chambers 19 with hydraulic fluid under high pressure, the inner gear 4 in a rotational movement relative to the outer toothed ring 3 are added. Of course, only a part of the fluid chambers 19 is connected to the high-pressure supply line. The other part of the fluid chambers 19 is connected to a fluid outlet, which may be substantially unpressurized with a hydraulic fluid reservoir.

In operation, however, the inner gear 4 rotates not only around the gear center 27. Rather, the gear center 27 follows a circular line about the central axis 26 of the gerotor motor 1. In other words, orbits the inner gear 4 in the course of its rotation about the central axis 26 of the gerotor motor 1.

The drive of external components takes place via the motor shaft 6 located on the right-hand side in FIG. 1. The motor shaft 6 has a connection region 28 designed differently depending on the specific embodiment. The motor shaft 6 is arranged in a housing 18. Opposite the housing 18, the motor shaft 6 performs a pure rotational movement about the central axis 26 of the housing 18 during operation. Motor shaft 6. The rotational movement of the motor shaft 6 is thus not superimposed by an orbital motion.

The motor shaft 6 is mounted with low friction in the shaft bore 17 at its two end regions located within the housing 18, in each case by a roller bearing ring 15.

To implement the combined rotational and orbital movement of the inner gear 4 of the gerotor gear set 2 to the pure rotational movement of the motor shaft 6 of the gerotor motor 1, a propeller shaft 5 is provided. The cardan shaft 5, which uses the gerotor motor 1 during operation, ensures a rotationally fixed connection between the inner gearwheel 4 of the gerotor gearwheel set 2 and the motor shaft 6. For this purpose, the cardan shaft 5 is in each case connected in a rotationally fixed manner to the motor shaft 6 or to the inner gearwheel 4 , In the present embodiment shown, the ends of the cardan shaft are each provided with sprockets 7, 8. The sprockets 7, 8 engage in each case in correspondingly formed sprockets 10, 29 of the motor shaft 6 and the inner gear 4 a.

During operation of the gerotor motor 1, the rotational movement superimposed by the orbiting movement of the inner gear 4 causes a nutating movement of the propeller shaft 5. In order to enable the propeller shaft 5 to effect this nutation movement, both in the motor shaft 6 and in the inner gear 4 of the gerotor Gear set 2 corresponding Kardanboh- ments 30, 31 provided. The gimbals 30, 31 are each divided into two subregions, namely in a provided with a sprocket 10, 29 area and an outer portion 11, 32, each having a substantially smooth wall.

The diameter of the gimbals 30, 31, in particular of the outer regions 11, 32 is selected such that between the propeller shaft 5 and the wall of the gimbal 30, 31 also taking into account Nutationswinkels α sufficient clearance remains. In the embodiment shown in FIG. 1, the outer regions 11, 32 of the gimbals 30, 31 each have a substantially constant diameter. In particular, in the case of larger nutation angles α, however, it is conceivable to provide a single or multiple stepped bore, possibly also a conical bore.

In the illustrated embodiment, an intermediate disc 33 between the motor shaft 6 receiving housing 18 and the gerotor gear set 2 is still provided. As the outer termination of the gerotor gear set 2 is a cover 34. The parts of the assembly are fastened by screws 24 which are inserted into corresponding screw holes 25 to each other. In the area of the screw holes 25, which is located in the housing 18, a thread is provided.

The control of the fluid chambers 19 of the gerotor gear set 2 by means of a rotary valve assembly 23 which is provided in the axial direction of the motor shaft 6. Depending on the angle of rotation of the motor shaft 6, a suitably selected part of the fluid chambers 19 by means of the rotary slide assembly 23 with a fluid inlet (not shown), which with the

High pressure part of a hydraulic oil supply system is connected, fluidly connected. The other part of the fluid chambers 19 is connected by means of the rotary valve arrangement 23 with an outlet port (not shown), which outputs the hydraulic oil, for example, in a standing under ambient pressure hydraulic oil reservoir.

The rotary valve assembly 23 comprises two formed on the outer side 35 of the motor shaft 6 radial channels 13 and 14, namely an inner radial channel 14 (right in the drawing) and an outer radial channel 13 (left in Fig. 1). Furthermore, 35 axial channels 12 are provided in certain radial areas of the motor shaft 6 on the outside thereof. These are partly with the outer radial channel 13, partly but also with the inner radial channel 14 in connection. At a corresponding angular position of the motor shaft 6, the axial channels 12 via channel openings 16 arranged on the inner wall 20 of the shaft bore 17, which are in turn connected to fluid passages 37 provided in the housing 18, effect a fluidic connection of the inner radial channel 14 and of the Outer radial channel 13 with the corresponding fluid chambers 19 of the gerotor gear set 2. Of course, this is the intermediate disc 33 is provided with a number of axially continuous, circularly arranged channels.

As can be clearly seen in Fig. 1, the total depth of the gimbal 30 in the motor shaft 6 in relation to the length range of the motor shaft 6, which is received by the housing 18, selected to be relatively small. In the exemplary embodiment illustrated in FIG. 1, the total depth of the cardan bore 30 is approximately 50% of the area of the motor shaft 6 received by the housing 18 (ie, the depth of the shaft bore 17). By virtue of this construction, it is possible that the entire inner radial channel 14 is supported by a support means, which is embodied in the form of a thickening of the material in the inner radial channel 14 shown in FIG. It is also possible to perform the motor shaft 6 in this area completely solid. However, in the present embodiment, a bore 38 has been provided, which serves to reduce the weight of the gerotor motor 1. Incidentally, this bore can also extend into that part of the motor shaft 6 which no longer lies within the housing 18 and can extend into the connection region 28. In the embodiment shown in Fig. 1, the bore 38 also serves by means of radially outwardly facing channels of the lubrication of the bearings 15. For this purpose, the bore 38 with one or more radial holes in connection, which in turn open into the shaft bore 17. The bore 38 in turn communicates with a low pressure port. As a result, leakage oil can flow past the inner radial channel on the rolling bearing 15 located on the right in FIG. 1, thereby ensuring lubrication of the bearing. The illustrated in Fig. 1 outer radial channel 13 and the axial channels 12 shown there are also supported by a support means. In the present case, this support means is in the form of the ring gear 8 of the gimbal 30. Due to the rib structure here is a reinforced support effect based on the static effect of such a rib structure.

Thanks to the support means, the motor shaft 6 in the region of the rotary slide valve assembly 23 can easily withstand the hydraulic pressure acting radially on the outer side 35 of the motor shaft 6. As a result, the deformation of the motor shaft can be smaller and the unavoidable in the region of the gap 36 between the outside 35 of the motor shaft 6 and the inner wall 20 of the shaft bore 17 leakage losses remain very small. The efficiency of the engine 1 increases thereby.

In the gerotor motor 1 shown in Fig. 1, the inner radial ring 14 is connected to the high-pressure wedge of the hydraulic system. Here, the distance to the relatively thin-walled outer region 11 of the formed in the motor shaft 6 Kardanbohrung 30 is particularly large. The

Leakage losses can be further reduced.

As can also be seen from FIG. 1, the outer radial channel 13 in the exemplary embodiment illustrated is mechanically supported only over approximately 75% of its width with a support means in the form of the toothed rim 10 of the motor shaft 6. Nevertheless, a surprisingly greatly reduced deflection of the outer side 35 of the motor shaft 6 is already achieved by this support, so that the gap 36 between the motor shaft 5 and shaft bore 17 remains very small and the leakage losses are correspondingly low. In addition, the deformations of the motor shaft 6 in this

Range also low because the corresponding area has only a small hydraulic oil pressure. Of course it is also possible 2008/000128

15 lends that a greater proportion of the width of the outer radial channel 13 is supported by support means. In particular, the entire outer radial channel 13 can be supported in this way.

In order to further increase the efficiency of the gerotor motor 1 shown in FIG. 1, a rolling bearing ring 15 is respectively arranged at the axial ends of the motor shaft 6 between the motor shaft 6 and the housing 18.

In order to compensate for the reduced depth of the shaft provided in the motor shaft 6 Kardanboh-O 30, it is on the one hand possible to increase the nutation angle α of the propeller shaft 6. Alternatively or additionally, it is also possible to increase the thickness of the gerotor gear set 2. It is possible to divide the provided in the inner gear 4 of the gerotor gear set 2 Kardanbohrung 31 into two subregions. Thus, a part of the cardan bore 31 may be provided with a toothed rim 29, the longitudinal grooves of which engage with a corresponding toothed rim 7 in the end region of the cardan shaft 5. A further, outer region 32 of the gimbal 31 formed in the inner gear 4 has a substantially unstructured inner wall, whose diameter corresponds to the "valley-valley" diameter of the sprocket 29 in the inner gear 4. Optionally, the inner diameter may be greater than the valley-valley diameter of the ring gear 7 are selected (the same applies to the gimbal 30 in the motor shaft 6). With the two mentioned possibilities, it is possible to further shorten the outer region 5 11 of the gimbal 30 formed in the motor shaft 6 with respect to the exemplary embodiment shown in FIG. 1 and, in the extreme case, to reduce it to zero.

An advantage of increasing the width of the gerotor gear set 2 o is that the torques generated by the fluid chambers 19 can be increased. With regard to the nutation angle α, depending on the specific application, a suitable Kom- promiss from low wear of the sprockets 7, 8, 10, 29 of propeller shaft 5, motor shaft 6 and inner gear 4 on the one hand and the smallest possible size of the gerotor motor 1 on the other hand, are selected.

Claims

claims

1. Rotary piston machine (1), in particular gerotor motor, with a gear (4), a this surrounding, with him displacement chambers (19) forming the toothed ring (3), a motor shaft (6) and the gear (4) and the motor shaft (6) rotatably connecting propeller shaft (5), wherein the motor shaft (6) and a housing receiving the motor shaft (18) a recesses (12, 13, 14) comprising rotary valve assembly (23) for controlling the

Displacement chambers (19), characterized in that the walls of the recesses (12, 13, 14) by at least one support means (6, 10) are supported.

2. Rotary piston machine according to claim 1, characterized in that at least one support means is formed as a material reinforcement (6).

3. Rotary piston machine according to claim 1 or 2, character- ized in that at least one support means as a static device

(10) is formed.

4. Rotary piston machine according to one of claims 1 to 3, characterized in that at least one support means is formed in the form of a material change.

5. Rotary piston machine according to one of claims 1 to 4, characterized in that extending at least one support means (6, 10) over at least 50% of the width of the corresponding recess (12, 13, 14).

6. Rotary piston machine according to one of claims 1 to 5, characterized in that the motor shaft (6) by peripheral rolling bearing devices (15) is supported.

7. Rotary piston machine according to one of claims 1 to 6, characterized in that the motor shaft (6) has recesses (30, 38), in particular a receiving space (30) for at least partially receiving the propeller shaft (5).

8. Rotary piston machine according to one of claims 1 to 7, characterized in that the rotationally fixed connection between propeller shaft (5) and motor shaft (6) and / or between propeller shaft (5) and gear (4) by a positive connection (7, 8, 10, 29) takes place.

9. Rotary piston machine according to one of claims 1 to 8, characterized in that the diameter of the propeller shaft (5) is at least 20% of the length thereof.

10. Rotary piston machine according to one of claims 1 to 9, characterized in that the rotary piston machine (1) has a preferred direction of rotation, wherein the high-pressure side (s) recess (s) (14) of the rotary valve arrangement (23) on a gear (4 ) spaced side of the motor shaft (6) are formed.