Radial piston pump, method of operating radial piston pump, and steering system

Abstract

The invention relates to a radial piston pump (1) for delivering a pressure medium to a consumer (2), having a housing (3) in which cylinder bores (5) are provided, which are arranged radially with respect to a longitudinal axis (4) and in each cylinder bore a radially displaceable piston (6) is arranged. The pistons (6) form a piston row (7) in a radial plane. The radial piston pump (1) further comprises an eccentric shaft (8) arranged coaxially to the longitudinal axis (4), which eccentric shaft sets the piston (6) in a linear oscillating reciprocating motion, in which pressure medium flows from a suction chamber (10) supplied with pressure medium through a suction port (11) into the cylinder chamber (12) through a suction opening (9) formed in the piston (6) in the region of bottom dead center of the stroke motion. As a result of the movement of the piston (6) towards the top dead center, the pressure medium flows out of the cylinder chamber (12) through the pressure opening (13) to the pressure outlet (14).

Description

Technical Field

[0001] The invention relates to a radial piston pump for conveying a pressure medium to a consumer part according to the preamble of claim 1, the radial piston pump having a housing in which cylinder bores are arranged radially relative to a longitudinal axis and in which a radially displaceable piston is arranged in each of the cylinder bores.

[0002] The invention furthermore relates to a method for operating a radial piston pump for conveying a pressure medium to a consumer according to the preamble of claim 12 .

[0003] The invention furthermore relates to a steering system according to claim 16 for a vehicle, in particular a utility vehicle, having at least two steerable wheel axles. Background Art

[0004] A generic radial piston pump for conveying pressure media is known from DE 10 2011 001 979 A1.

[0005] For further prior art, reference is also made to DE 10 2011 053 145 A1.

[0006] Radial piston pumps are often used in motor vehicles and serve, for example, as lubrication pumps for internal combustion engines or for the vehicle's gearbox, as pressure medium pumps for hydraulic actuators for providing power as a steering aid or for initiating actuating movements on a clutch or in an active suspension of the vehicle. If higher pressure levels are required at the hydraulic consumer, radial piston pumps are used in preference to vane pumps.

[0007] A radial piston pump has a housing in which cylinder bores are arranged radially relative to a longitudinal axis. A radially movable piston is arranged in each cylinder bore. Typically, in radial piston pumps, a pressure medium, such as hydraulic oil or the like, is sucked into a displacement chamber or cylinder chamber between the piston and the cylinder bore via a suction opening, which is arranged radially for the respective cylinder bore, and the pressure medium is discharged through a pressure opening, which is preferably arranged in the center of each cylinder bore. Here, a wall section of the piston interacts with a wall section of the cylinder bore.

[0008] The radial piston pump therefore delivers pressure medium discontinuously into the partial volume with each rotation of the drive cam or of the eccentric shaft, which causes a displacement movement of each piston in the corresponding cylinder bore.

[0009] DE 4336673 A describes a radial piston pump having a plurality of pistons which are inserted into cylinder bores of a pump housing, wherein each piston is loaded by a spring which rests on a stop which closes the cylinder bore.

[0010] Radial piston pumps have proven to be advantageous for many applications, in particular in vehicles and especially also in utility vehicles; however, it would be desirable to further optimize radial piston pumps in order to expand their application possibilities.

[0011] The prior art describes a steering system for a vehicle, in particular a multi-purpose vehicle and in particular a multi-purpose vehicle for the agricultural sector, which has at least two steerable axles. In normal operation, the steerable axles are each deflected by an electric steering device and / or a hydraulic steering device, so that the multi-purpose vehicle can be steered or controlled at two axles. For such a vehicle, it is necessary to configure the steering system so that in addition to the electric steering device and / or the hydraulic steering device that ensures the deflection of the steerable axles, in particular the deflection of the wheels of the axles in normal operation, there is also an emergency steering function. For this purpose, it is known that an emergency steering pump is assigned to each axle in order to allow the steerable axles to remain steerable or controllable in an emergency. The arrangement or provision of such an emergency steering pump (which can be a radial piston pump) requires corresponding costs and corresponding complexity of assembly and maintenance. Summary of the invention

[0012] The invention is based on the object of providing a radial piston pump which is improved compared to the prior art, in particular has improved functionality.

[0013] According to the invention, this object is achieved by claim 1 .

[0014] Furthermore, the invention is based on the object of providing a method for operating a radial piston pump which is improved compared to previous methods, in particular has an improved functionality.

[0015] This object is achieved according to the invention by claim 12 .

[0016] Furthermore, the invention is based on the object of providing a steering system for a vehicle with at least two steerable axles, in particular a multi-purpose vehicle, wherein the at least two steerable axles remain deflectable even in emergency situations, wherein the steering system is simple and economical to produce and easy to maintain.

[0017] This object is achieved according to the invention by claim 16 .

[0018] The radial piston pump for delivering a pressure medium to a consumer according to the present invention has a housing in which a cylinder bore is arranged radially relative to a longitudinal axis and a piston capable of radial displacement is arranged in each of the cylinder bores. The piston forms a piston row located in a radial plane. The radial piston pump further has an eccentric shaft arranged coaxially with the longitudinal axis, which sets the piston to a linear oscillating reciprocating motion, wherein the pressure medium flows into the cylinder chamber from a suction chamber supplied with a pressure medium through a suction port through a suction opening formed in the piston in the region of the lower dead center of the stroke motion. Due to the movement of the piston toward the upper dead center, the pressure medium flows out of the cylinder chamber through the pressure opening to the pressure outlet.

[0019] According to the present invention, at least one additional piston row is arranged in a plane parallel to the piston row, wherein an additional cylinder bore is arranged in the housing, the pistons of the additional piston row are radially displaceably arranged in each of the cylinder bores, and wherein the eccentric shaft sets the pistons of the additional piston row to a linear oscillating reciprocating motion.

[0020] The design of the radial piston pump according to the invention enables at least one further piston row to be arranged in a plane parallel to the piston row (which is arranged in conventional radial piston pumps and is sometimes also referred to as the first piston row in the context of the invention), which leads to an expansion of the functionality or application possibilities of such a radial piston pump. By means of this further piston row (which is sometimes also described as the second piston row for the purpose of differentiation in the context of the invention), a second pressure medium flow can be generated, which can be superimposed on the first pressure medium flow generated by the first piston row or replace the first pressure medium flow as required, or can be used permanently or when required to supply pressure medium to or operate further consumables, which are sometimes also referred to as second consumables in the context of the invention.

[0021] By means of the solution according to the invention, it is possible to easily, reliably and economically implement further rows of pistons by providing further cylinder bores in the housing, the pistons of the further rows of pistons being arranged radially displaceably in each of the cylinder bores. Thus, the eccentric shaft provided in any case for setting the pistons of the first row of pistons to a linear oscillating reciprocating motion can also be used for setting the pistons of the further rows of pistons to a linear oscillating reciprocating motion.

[0022] Within the scope of the invention, it can also be provided that not only a further piston row is provided, but also a third, fourth or even further piston row is provided, each of which extends parallel to the plane of the first piston row, i.e. each of which extends in a radial plane relative to the longitudinal axis or the eccentric shaft.

[0023] Within the scope of the invention, it can be provided that the pistons of the further piston row are arranged offset or shifted by a defined center point angle or a defined arc relative to the pistons of the first piston row, whereby in some cases the quietness and / or stability of the operation of the radial piston pump can be improved.

[0024] In the context of the invention, it is provided that each piston row has at least two pistons, preferably two to sixteen pistons, in particular four to twelve pistons, and quite particularly preferably six to ten, in particular eight pistons, are provided per piston row. The pistons of the piston rows are preferably arranged with equal angular spacing.

[0025] In the context of the invention, it is preferably provided that all piston rows have the same number of pistons, preferably six to ten, in particular eight pistons. However, depending on the application, it is also conceivable that a piston row (eg the first piston row) has more pistons than another piston row.

[0026] Advantageously, the eccentric shaft is configured as a double eccentric shaft having at least one first eccentric region which sets the pistons of one piston row in a reciprocating motion and at least one second eccentric region which sets the pistons of another piston row in a reciprocating motion.

[0027] It can also be provided that the eccentric shaft has a third, fourth or further eccentric region. It has been found that it can be advantageous if the eccentric regions, in particular the first eccentric region and the second eccentric region, are not formed identically. This can achieve, for example, that the stroke of a piston of a piston row (for example the first piston row) is greater than the stroke of a piston of another piston row (for example the second piston row) (or vice versa).

[0028] However, it can also be provided that the eccentric regions are formed identically; this may be the case, in particular if a uniform stroke is desired, or if a change or adjustment of the stroke or the stroke movement of the piston is to be achieved by other measures, for example by sliding rings and / or sliding bushings arranged between the eccentric shaft or the eccentric region of the eccentric shaft and the piston of the piston row.

[0029] Within the scope of the invention, it can also be provided that the slide ring and / or the slide bushing forms a corresponding eccentric region.

[0030] According to the present invention, it can further be provided that the pressure medium flows from the suction chamber into the cylinder chamber through a suction opening formed in the piston of another piston row in the region of the bottom dead center of the stroke movement, and the pressure medium flows out of the cylinder chamber via the pressure opening due to the movement of the piston toward the top dead center.

[0031] It has proven to be advantageous if the pistons of the further piston row are arranged similarly to the pistons of the first piston row and in particular the same suction chamber is used for sucking pressure medium into the corresponding cylinder chamber (or displacement chamber).

[0032] The pressure medium also escapes or flows out of the respective cylinder chamber via pressure openings, the arrangement or form of which has long been known in the prior art, in which context reference is explicitly made to DE 10 2011 011 979 A1.

[0033] It has been found that it is advantageous if the cylinder bore of the piston receiving the piston row is open on its side facing the eccentric towards the suction part or suction chamber and is preferably pressure-tightly sealed on its opposite side by a corresponding closing stop, which is drop-shaped in longitudinal section. Obviously, the invention is not limited to this and other designs can be advantageously implemented. In the case of providing closing stops, it may be advantageous if the end of a coil compression spring rests on the inner side of each closing stop. The other end of the coil compression spring can preferably rest on the bottom plate of the internal hollow piston and apply pressure to the piston. This structure, in particular also using a coil compression spring, can also be applied independently of the design of the closing stop.

[0034] This is a particularly advantageous structural design which is known from the prior art and which is also suitable in particular for the radial piston pump according to the invention.

[0035] It is pointed out that the term "cylinder bore" does not necessarily mean that it must be produced using a drilling process; although it is advantageous to produce the cylinder bore by means of a drilling process, the cylinder bore can also be arranged in another way.

[0036] According to the invention, it can further be provided that a further pressure outlet is formed in the housing and that the pistons of the further row of pistons deliver the pressure medium to the further pressure outlet.

[0037] It has proven to be advantageous if a further pressure outlet is formed in the housing of the radial piston pump and if the pistons of the further piston row deliver pressure medium to the further pressure outlet.

[0038] In principle, it is also possible for the pistons of the further row of pistons to deliver pressure medium to a pressure outlet at which the pistons of the first row of pistons also discharge the pressure medium they have delivered.

[0039] Insofar as more than one further row of pistons is provided, in some cases further pressure outlets may also be provided, for example a third pressure outlet and a fourth pressure outlet.

[0040] According to the invention, it can further be provided that the pressure outlet is connected to the first consumer and the further pressure outlet is connected to the second consumer in order to convey the pressure medium from the respective pressure outlet to the respective connected consumer.

[0041] Since the further pressure outlet, which can also be referred to as second pressure outlet, is connected to the second consumer, a further or second pressure medium flow or pressure medium circuit can be produced in a particularly advantageous manner.

[0042] In an alternative embodiment also according to the invention, it can also be provided that the pressure outlet and the further pressure outlet are connected to the same consumer in order to deliver pressure medium to the same consumer.

[0043] This design has also been proven to be suitable.

[0044] It is advantageous if the control device is provided to deliver pressure medium from only one or both pressure outlets to the same consumer as required.

[0045] The control device can be configured to deliver only the pressure medium delivered by the first piston row or only the pressure medium delivered by the further piston row to the same consumer, as required.

[0046] This can ensure, for example, that if the consumer only needs a small pressure medium flow or only needs a small volume of pressure medium, the consumer is supplied with pressure medium from only one piston row, preferably from the piston row that delivers a smaller volume. It can be provided that the pistons of the other piston rows are designed to deliver a larger volume. Therefore, the control device can provide the consumer with a suitable or optimized pressure medium flow from one or the other piston row as required. In some cases, it can also be provided that the pressure medium delivered by two piston rows is supplied to the consumer, particularly if there is a particularly high demand.

[0047] If the two piston rows deliver different volumes, or if the pressure medium from the two piston rows reaches the consumer at different pressures, such a controller may be suitable. However, such a design may also be suitable if the two piston rows are formed identically or deliver the same volume of pressure medium.

[0048] Within the scope of the invention, piston rows can have identical or different geometric delivery volumes.

[0049] According to the present invention, it can be provided that the piston row is configured so that: the volume of pressure medium delivered by the piston row when the eccentric shaft rotates is different from the volume delivered by another piston row, and / or the radial piston pump is configured so that: the pressure of the pressure medium originating from the piston row is different from the pressure of the pressure medium originating from another piston row.

[0050] It has proven to be advantageous if the piston rows deliver different volumes and / or if the pressure medium originating from the piston rows, or the corresponding pressure medium flows, have different pressures.

[0051] This design may be suitable if the piston rows supply pressure medium to the same consumer, and if the piston rows supply pressure medium to different consumers. In the latter case, in particular, different volumes of pressure medium or pressure medium at different pressures can be set to suit the specific circumstances of the respective consumer, without requiring a second radial piston pump for this case.

[0052] Advantageously, a dedicated sliding ring is provided for each piston row, wherein each sliding ring is arranged between the eccentric shaft and the associated piston row.

[0053] The sliding ring can be directly arranged on the eccentric shaft. Specifically, the sliding ring can be directly arranged on the corresponding eccentric area of ​​the eccentric shaft. The sliding ring can preferably act directly or indirectly on the bottom plate of the piston of the corresponding piston row.

[0054] The advantage of this sliding ring is that in addition to the improved sliding properties, the stroke of the pistons of the corresponding piston row can be easily changed without having to change the eccentric shaft. This allows in particular to use the same eccentric shaft for different radial piston pumps and the stroke of the pistons can be adapted by means of the sliding ring mounted to the eccentric shaft.

[0055] In the context of the radial piston pump according to the invention, the sliding rings allow in particular the eccentric regions of the piston rows to be formed identically and different strokes to be set by means of different sliding rings.

[0056] Advantageously, the thickness of the sliding ring of one piston row in the radial direction differs from the thickness of the sliding ring of another piston row in the radial direction.

[0057] Alternatively or in addition to the sliding ring, a sliding bushing can also be provided.

[0058] According to the present invention, it can be further provided that the radial piston pump is configured as an emergency steering pump for a vehicle, in particular a multi-purpose vehicle, wherein a row of pistons is configured to deliver pressure medium to a wheel steering gear or a steering cylinder of a steering system of a first wheel axle, and another row of pistons is configured to deliver pressure medium to a wheel steering gear or a steering cylinder of a steering system of a second wheel axle.

[0059] It has proven particularly suitable that the radial piston pump is configured as an emergency steering pump for a vehicle, in particular a utility vehicle, preferably an agricultural utility vehicle. It has been found that, in particular in a utility vehicle with two steerable axles, there is a need for an emergency steering pump. In the prior art, a separate emergency steering pump is used for each axle and is used to steer the axle if the (electric and / or hydraulic) steering device of the steering system actually provided for this axle has a fault or requires support.

[0060] The function of an emergency steering pump is known in principle from the prior art, in particular for deflecting a steerable wheel axle. To this end, the wheels of the axle are usually deflected. It can be provided that the wheel steering gear is pressurized with pressure medium from the emergency steering pump or that the steering cylinder of the steering system or steering device is pressurized with pressure medium.

[0061] The use of the radial piston pump according to the invention as an emergency steering pump is very particularly suitable, because in this way, considerable costs can be saved without fearing a loss of functionality. In addition, the maintenance and assembly complexity is also reduced.

[0062] The present invention also relates to a method for operating a radial piston pump for delivering a pressure medium to a consumer, wherein the radial piston pump has a housing in which cylinder bores are provided, the cylinder bores being radially arranged relative to a longitudinal axis, and a radially displaceable piston being arranged in each of the cylinder bores, wherein the pistons form a piston row located in a radial plane, and wherein the pistons are set to a linear oscillating reciprocating motion by an eccentric shaft arranged coaxially with the longitudinal axis, and wherein, under a vacuum generated by the movement of the piston toward a bottom dead center, the pressure medium flows from a suction chamber supplied with the pressure medium through a suction port into a cylinder chamber through a suction opening of the piston in the bottom dead center region of the stroke movement, and wherein, when the piston moves toward a top dead center, the pressure medium is delivered to a pressure outlet via the pressure opening.

[0063] According to the invention, in the context of the method, at least one further piston row is arranged in a plane parallel to the piston row. In this case, a further cylinder bore is provided in the housing, the pistons of which are radially displaceably arranged in each of the cylinder bores. The pistons of the further piston row are set in a linear oscillating reciprocating motion by an eccentric shaft. The pressure medium delivered by the piston row and the further piston row is supplied to the same consumer, or the pressure medium delivered by the piston row is supplied to a first consumer and the pressure medium delivered by the further piston row is supplied to a second consumer.

[0064] The method for operating a radial piston pump according to the invention particularly advantageously allows pressure medium from a piston row and at least one further piston row, or from two piston rows, to be supplied to the same consumer, or pressure medium is supplied to two consumers, i.e. a first consumer and a second consumer, each consumer coming from a respective piston row. Thus, the operation of the radial piston pump according to the invention allows the radial piston pump to achieve greater functionality. The structure of the radial piston pump particularly advantageously allows a simple, economical and robust construction. With regard to further advantages, specific reference is made to the statements made above and below with regard to the radial piston pump.

[0065] It is advantageously provided that when pressure medium is delivered to the same consumer, as required, only pressure medium delivered by the first piston row or only pressure medium delivered by the further piston row or pressure medium delivered by both piston rows is supplied to the consumer.

[0066] According to the invention, within the scope of the method, it can further be provided that the volume of pressure medium delivered by a piston row when the eccentric shaft rotates is different from the volume delivered by another piston row, and / or the pressure of the pressure medium originating from a piston row is different from the pressure of the pressure medium originating from another piston row.

[0067] The method according to the invention thus allows two different consumers to be operated or loaded with pressure medium of different pressures and / or volumes by one radial piston pump, or the pressure medium flow to be adjusted accordingly. The method according to the invention also allows the same consumer to be operated or loaded with pressure medium of different pressures and / or volumes, or the pressure medium flow to be adjusted accordingly, as required.

[0068] According to the present invention, also within the scope of the method, it can be provided that during operation of the radial piston pump, the pressure medium delivered by the piston row is supplied to a first consumer and the pressure medium delivered by the other piston row is supplied to a second consumer, the first consumer being a first steerable axle of a multi-purpose vehicle and the second consumer being a second steerable axle of the multi-purpose vehicle, wherein it is preferably provided that the radial piston pump is configured as an emergency steering pump, wherein the first consumer is a wheel steering gear or a steering cylinder of a steering system of a first axle and the second consumer is a wheel steering gear or a steering cylinder of a steering system of said second axle.

[0069] The method according to the invention is particularly suitable for supplying a first consumer and a second consumer. Quite particularly, the method according to the invention is suitable if the two consumers are a first steerable wheel axle and a second steerable wheel axle and a radial piston pump is used as an emergency steering pump.

[0070] The invention also relates to a steering system for a vehicle, in particular for a multi-purpose vehicle, having at least two steerable axles, each of which can be deflected by a corresponding electric steering device and / or hydraulic steering device in normal operation. The steering system also has an emergency steering pump, which is configured according to the invention as a radial piston pump according to any one of claims 1 to 11 or is operated in a method according to any one of claims 12 to 15. In the steering system according to the invention, a pressure line is provided to supply the pressure medium delivered by the piston row to the wheel steering gear or the steering cylinder of the steering device of the first wheel axle. In addition, a further pressure line is provided to supply the pressure medium delivered by the further piston row to the wheel steering gear or the steering cylinder of the steering device of the second wheel axle.

[0071] It has been shown that a steering system configured in this way is particularly suitable for utility vehicles, preferably for agricultural utility vehicles. With such a steering system, an emergency steering function can be realized in a simple and economical manner. It is sufficient if the emergency steering pump is configured as a radial piston pump and is designed according to the invention. The use of two radial piston pumps is not necessary. This significantly reduces costs and assembly complexity. In addition, the weight of the utility vehicle is reduced, and maintenance costs and repair costs are also reduced.

[0072] It is pointed out that the term "pressure line" does not mean that a plurality of pressure lines leading to the respective consumer need to be provided; in some cases only one pressure line leading to the consumer may be sufficient.

[0073] Features described in connection with one of the subjects of the invention (i.e. caused by the radial piston pump according to the invention, the method according to the invention for operating a radial piston pump, or the steering system according to the invention) can also be advantageously implemented for the other subjects of the invention. Similarly, advantages described in connection with one of the subjects of the invention can be understood to also relate to the other subjects of the invention.

[0074] In addition, it is pointed out that terms such as "comprising", "including" or "having" do not exclude other features or steps. Furthermore, terms such as "a" or "said" referring to a single step or feature do not exclude multiple features or steps, and vice versa.

[0075] However, in a linguistically concise embodiment of the present invention, it may also be provided that the features presented by the terms "comprising", "including" or "having" are comprehensively listed. Thus, in the context of the present invention, one or more feature lists may be considered comprehensive, for example when each claim is considered separately. The present invention may, for example, consist exclusively of the features listed in claim 1.

[0076] It is pointed out that terms such as “first” or “second” are mainly used for the reason of distinguishability of corresponding apparatus or method features, and do not necessarily indicate that the features are mutually conditional or independent with respect to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Exemplary embodiments of the present invention are described in more detail below with reference to the accompanying drawings.

[0078] In the attached picture:

[0079] Figure 1 shows a cross section through a possible embodiment of a radial piston pump; and

[0080] Figure 2 A schematic diagram of the supply of two consumables by a radial piston pump according to the invention is shown. DETAILED DESCRIPTION

[0081] Radial piston pumps and their basic function have been known from the prior art for some time, for which purpose reference is made in particular to the general laid-open specification DE 10 2011 001 979 A1.

[0082] As from Figure 1 and Figure 2 As is evident from the figure, the radial piston pump 1 according to the invention for conveying a pressure medium to a consumer 2 (also referred to below as first consumer 2 ) has a housing 3 in which a plurality of cylinder bores 5 arranged radially with respect to a longitudinal axis 4 are provided.

[0083] In this exemplary embodiment, six to ten, preferably eight, cylinder bores 5 are provided. A radially displaceable piston 6 is arranged in each of the cylinder bores 5. The pistons 6 form a piston row 7 lying in a radial plane. The radial plane here refers to the longitudinal axis 4. In this exemplary embodiment, the piston row 7 is also described as the first piston row 7.

[0084] The radial piston pump 1 furthermore has an eccentric shaft 8 arranged coaxially with the longitudinal axis 4 and sets the piston 6 in a linear oscillating reciprocating motion. When the piston 6 is in the lower dead center region of the stroke motion, the pressure medium is sucked into the cylinder chamber 12 from the suction chamber 10 supplied with the pressure medium via the suction port 11 through the suction opening 9 formed in the piston 6. The cylinder chamber 12 can be described here as a displacement chamber.

[0085] By the movement of the piston 6 toward the top dead center, the pressure medium is pressed out of the cylinder chamber 12 to the pressure outlet 14 through the pressure opening 13, or flows in the direction of the pressure outlet 14. By deviating from the design of the conventional radial piston pump, as illustrated in the exemplary embodiment, for example, the radial piston pump 1 according to the present invention has at least one additional piston row 15 arranged in a plane parallel to the first piston row 7. The additional piston row 15 is also referred to as the second piston row 15. Additional cylinder bores 16 are provided in the housing 3, and the pistons 17 of the additional piston row 15 are radially displaceably arranged in each of these cylinder bores 16. The eccentric shaft 8 sets the piston 17 of the other piston row 15 to a linear oscillating reciprocating motion.

[0086] It should be noted that the radial piston pump 1 illustrated in this exemplary embodiment is particularly advantageous, although deviations therefrom are possible. Specifically, a third piston row or a fourth piston row or even another piston row may also be provided, which are preferably identical in structure to the first piston row 7 or the second piston row 15.

[0087] In the exemplary embodiment, it is provided that the second piston row 15 also has six to ten, preferably eight, pistons 17 , ie a corresponding number of cylinder bores 16 are provided.

[0088] In the exemplary embodiment, it is further provided that the pressure medium flows into the cylinder chamber 12 through the suction opening 9 formed in the piston 17 in the region of the bottom dead center of the stroke movement. When the piston 17 moves toward the top dead center, the pressure medium flows out of the cylinder chamber 12 again through the pressure opening 13 or is pressed out.

[0089] The structure of the cylinder bore 16 and the piston 17 may preferably be the same as that of the cylinder bore 5 and the piston 6 .

[0090] In an exemplary embodiment, it may be provided that the cylinder bore 5 or the piston 6 has a different diameter and / or a different length than the cylinder bore 16 or the piston 17 .

[0091] In the exemplary embodiment, the eccentric shaft 8 is configured as a double eccentric shaft. The eccentric shaft 8 has a first eccentric region 18, which sets the piston 6 of the first piston row 7 to reciprocate when the eccentric shaft rotates. In addition, the eccentric shaft 8 has a second eccentric region 19 that sets the piston 17 of the second piston row 15 to reciprocate.

[0092] As from Figure 1 It is also evident that for each piston row 7, 15, a dedicated sliding ring 20 is provided. In the exemplary embodiment, the sliding ring 20 is arranged on the eccentric shaft 8, more precisely on the first eccentric area 18 and the second eccentric area 19. The sliding ring 20 is positioned between the eccentric shaft 8 or the eccentric area 18, 19 and the corresponding piston row 7 or piston row 15.

[0093] In the exemplary embodiment, the two slide rings 20 are shown to have the same thickness in the radial direction. However, it can also be provided that the slide rings 20 have different thicknesses in the radial direction.

[0094] As from Figure 1 As is evident in the figure, the radial piston pump 1 has a further pressure outlet 21 formed in the housing 3. The further pressure outlet 21, which may also be referred to as second pressure outlet 21, is supplied with pressure medium by the pistons 17 of the second piston row 15.

[0095] In an exemplary embodiment, it may be provided that the pressure outlet 14 , which may also be referred to as the first pressure outlet 14 , and the second pressure outlet 21 serve to deliver pressure medium to the same consumer 2 .

[0096] However, in the exemplary embodiment, a design is shown in which a first pressure outlet 14 is connected to a first consumer 2 and a second pressure outlet 21 is connected to a second consumer 22. Thus, the respective pressure outlets 14, 21 can deliver pressure medium to the respective connected consumer 2 or consumer 22.

[0097] In an exemplary embodiment, it can be provided that the piston rows 7, 15 are configured such that the volume of pressure medium delivered by the first piston row 7 differs from the volume delivered by the second piston row 15 when the eccentric shaft 8 rotates. Alternatively and / or additionally, it can also be provided that the radial piston pump 1 is configured such that the pressure of the pressure medium originating from the first piston row 7 differs from the pressure of the pressure medium originating from the further / second piston row 15.

[0098] In the exemplary embodiment, for simplicity, it is provided that the piston rows 7, 15 supply or pressurize the consumer 2, 22 with the same volume and the same pressure of the pressure medium at a constant rotation of the eccentric shaft. However, depending on the consumer 2, 22, it may be appropriate to select different volumes or different pressures for the respective consumer 2, 22.

[0099] The present exemplary embodiment also serves to disclose a method according to the invention for operating a radial piston pump 1 .

[0100] Operation of the radial piston pump 1 is particularly suitable if the first consumer 2 is a first steerable axle of a utility vehicle (not shown in greater detail), in particular an agricultural utility vehicle, and the second consumer 22 is its second steerable axle. In principle, this can also be a vehicle in general.

[0101] The method according to the invention is particularly suitable if the radial piston pump 1 is configured as an emergency steering pump, wherein the first consumer 2 can be a wheel steering gear or a steering cylinder of a steering device of a first wheel axle and the second consumer 22 can be a wheel steering gear or a steering cylinder of a steering device of a second wheel axle.

[0102] Figure 2 The diagram shows a circuit of a radial piston pump 1, wherein pressure medium flows from the pressure outlet 14 to the first consumer 2 and from the first consumer 2 back to the pressure medium reservoir 23. From the second pressure outlet 21, pressure medium is delivered to the second consumer 22 and from the second consumer 22 back to the pressure medium reservoir 23 again. Figure 2 Also shown as an example is a drive shaft or eccentric shaft 8 .

[0103] Figure 2 It is also shown that the consumer 2 , 22 may be part of a steering system 24 .

[0104] The exemplary embodiment also serves to disclose an exemplary steering system 24 for a vehicle having at least two steerable axles, in particular a utility vehicle and quite particularly an agricultural utility vehicle, wherein Figure 2 In the exemplary embodiment of the at least two steerable axles can be consumables 2, 22. In a manner not shown in detail, the two steerable axles can each be deflected in normal operation by an electric steering device and / or a hydraulic steering device as part of the steering system 24.

[0105] The radial piston pump 1 is used here as an emergency steering pump which is configured according to the invention and / or is operated using the method according to the invention.

[0106] In the context of the steering system 24, a pressure line is provided for supplying the pressure medium delivered by the first piston row 7 to the wheel steering gear or steering cylinder (=consumer 2) of the steering device of the first wheel axle. In addition, a further pressure line can be provided for supplying the pressure medium delivered by the second piston row 15 to the wheel steering gear or steering cylinder (=consumer 22) of the steering device of the second wheel axle.

[0107] Figure 1The radial piston pump 1 shown in is preferably a suction-regulated radial piston pump with a double-row design. The radially arranged pistons 6, 17 are set to a linear oscillating reciprocating motion by a common rotating double eccentric shaft 8 in combination with a spring 25 in the pistons 6, 17. At the bottom dead center of the stroke movement, the preferably radial suction opening in the piston 6 or the piston 17 (which can be a suction hole) immerses in the suction chamber 10, which can also be described as an eccentric chamber. Under the vacuum generated in the cylinder chamber 12 by the movement of the piston 6, 17 to the bottom dead center, the pressure medium flows into the cylinder chamber 12 when the preferably radial suction opening 9 is opened. The pressure medium is preferably a hydraulic fluid, in particular oil.

[0108] When the piston 6, 17 moves toward the top dead center, the pressure medium is delivered to the pressure outlet 14 or the pressure outlet 21 through the pressure opening 13 (which can also be called the outlet hole) and the preferably arranged non-return valve (not specified in more detail). Each pressure outlet 14, 21 is connected to the piston row 7, 15. This allows the pressure medium to be supplied to separate consumer parts 2, 22. The principle of suction regulation allows the delivery amount of the pressure medium to be changed by an appropriate combination of the eccentricity of the piston 6, 17, the sliding ring 20 and the eccentric shaft 8. Therefore, different delivery amounts can be set for each circuit. Due to the common drive, the eccentric shaft 8 and the suction port 11, a flexible dual-circuit configuration with a compact structure is possible.

[0109] Reference numerals list

[0110] 1 Radial piston pump

[0111] 2(First) Consumables

[0112] 3 Shell

[0113] 4 Longitudinal axis

[0114] 5 cylinder bore

[0115] 6 Piston

[0116] 7 (1st) piston row

[0117] 8 Eccentric shaft

[0118] 9 Suction opening

[0119] 10 Suction chamber

[0120] 11 Suction port

[0121] 12 cylinder chamber

[0122] 13 Pressure opening

[0123] 14 (First) Pressure Outlet

[0124] 15 (additional / second) piston row

[0125] 16 (additional) cylinder bores

[0126] 17 (additional) piston (piston 15)

[0127] 18 First eccentric area

[0128] 19 Second eccentric area

[0129] 20 Sliding ring

[0130] 21 (Additional / Second) Pressure Outlet

[0131] 22 (Second) Consumables

[0132] 23 Pressure medium storage

[0133] 24 Steering system

[0134] 25 Spring

[0135] Q Volume

[0136] P pressure

Claims

1. A radial piston pump (1) for delivering a pressure medium to a consumer (2), the radial piston pump (1) having a housing (3) in which a cylinder bore (5) is arranged radially relative to a longitudinal axis (4), and in each of the cylinder bores (5) a radially displaceable piston (6) is arranged, wherein the pistons (6) form a piston row (7) located in a radial plane, and the radial piston pump (1) has an eccentric shaft (8) which is arranged coaxially with the longitudinal axis (4) and sets the pistons (6) to a linear oscillating reciprocating motion, wherein: The pressure medium flows from a suction chamber (10) supplied with the pressure medium via a suction port (11) into a cylinder chamber (12) through a suction opening (9) formed in the piston (6) in the region of the bottom dead center of the stroke movement, and the pressure medium flows out of the cylinder chamber (12) through a pressure opening (13) to a pressure outlet (14) due to the movement of the piston (6) towards the top dead center, It is characterized in that At least one additional piston row (15) is arranged in a plane parallel to the piston row (7), wherein additional cylinder holes (16) are arranged in the housing (3), and a piston (17) of the additional piston row (15) that can be radially displaced is arranged in each of the additional cylinder holes (16), and wherein the eccentric shaft (8) sets the piston (17) of the additional piston row (15) to a linear oscillating reciprocating motion.

2. The radial piston pump according to claim 1, It is characterized in that The eccentric shaft (8) is configured as a double eccentric shaft having at least one first eccentric region (18) for setting the piston (6) of the piston row (7) to reciprocate and at least one second eccentric region (19) for setting the piston (17) of the other piston row (15) to reciprocate.

3. The radial piston pump according to claim 1 or 2, It is characterized in that Pressure medium flows from the suction chamber (10) into the cylinder chamber (12) through a suction opening (9) formed in the piston (17) of the other piston row (15) in the region of the bottom dead center of the stroke movement, and the pressure medium flows out of the cylinder chamber (12) via a pressure opening (13) due to the movement of the piston (17) towards the top dead center.

4. A radial piston pump according to claim 1, 2 or 3. It is characterized in that A further pressure outlet (21) is formed in the housing (3), and the pistons (17) of the further piston row (15) deliver pressure medium to the further pressure outlet (21).

5. The radial piston pump according to claim 4, It is characterized in that The pressure outlet (14) is connected to a first consumer (2), and the further pressure outlet (21) is connected to a second consumer (22) in order to convey pressure medium from the respective pressure outlet (14, 21) to the connected consumers (2, 22).

6. The radial piston pump according to claim 4, It is characterized in that The pressure outlet (14) and the further pressure outlet (21) are connected to the same consumer (2) in order to deliver the pressure medium to the same consumer (2).

7. The radial piston pump according to claim 6, It is characterized in that A control device is provided to deliver pressure medium from only one or both pressure outlets (14, 21) to the same consumer (2) as required.

8. A radial piston pump according to any one of claims 1 to 7, It is characterized in that The piston row (7, 15) is configured so that the volume of pressure medium delivered by the piston row (7) when the eccentric shaft (8) rotates is different from the volume delivered by the other piston row (15), and / or the radial piston pump (1) is configured so that the pressure of the pressure medium originating from the piston row (7) is different from the pressure of the pressure medium originating from the other piston row (15).

9. A radial piston pump according to any one of claims 1 to 8, It is characterized in that A dedicated sliding ring (20) is provided for each piston row (7, 15), wherein the sliding ring (20) is arranged between the eccentric shaft (8) and the corresponding piston row (7, 15).

10. The radial piston pump according to claim 9, It is characterized in that The thickness of the sliding ring (20) of the piston row (7) in the radial direction is different from the thickness of the sliding ring (20) of the other piston row (15) in the radial direction.

11. A radial piston pump according to any one of claims 1 to 10, It is characterized in that The radial piston pump (1) is configured as an emergency steering pump for a vehicle, in particular a multi-purpose vehicle, wherein the piston row (7) is configured to deliver pressure medium to a wheel steering gear or a steering cylinder of a steering system of a first wheel axle, and the further piston row (15) is configured to deliver pressure medium to a wheel steering gear or a steering cylinder of a steering system of a second wheel axle.

12. A method for operating a radial piston pump (1) for conveying a pressure medium to a consumer (2), wherein: The radial piston pump (1) comprises a housing (3) in which cylinder bores (5) are arranged radially with respect to a longitudinal axis (4), and a radially displaceable piston (6) is arranged in each of the cylinder bores (5), wherein the pistons (6) form a piston row (7) located in a radial plane, and wherein the pistons (6) are set to a linear oscillating reciprocating motion by an eccentric shaft (8) arranged coaxially with the longitudinal axis (4), and wherein, under a vacuum generated by the movement of the piston (6) toward the bottom dead center, a pressure medium flows from a suction chamber (10) supplied with the pressure medium through a suction port (11) into a cylinder chamber (12) through a suction opening (9) of the piston (6) in the bottom dead center region of the stroke movement, and wherein, when the piston (6) moves toward the top dead center, the pressure medium is delivered to a pressure outlet (14) via a pressure opening (13), It is characterized in that At least one additional piston row (15) is arranged in a plane parallel to the piston row (7), and an additional cylinder hole (16) is arranged in the housing (3), a piston (17) of the additional piston row (15) that can be radially displaced is arranged in each of the additional cylinder holes (16), and the piston (17) of the additional piston row (15) is set to linear oscillating reciprocating motion through the eccentric shaft (8), so that the pressure medium delivered by the piston row (7) and the additional piston row (15) is supplied to the same consumer (2) or the pressure medium delivered by the piston row (7) is supplied to the first consumer (2) and the pressure medium delivered by the additional piston row (15) is supplied to the second consumer (22).

13. The method according to claim 12, It is characterized in that When the pressure medium is delivered to the same consumer (2), only the pressure medium delivered by the first piston row (7) or only the pressure medium delivered by the other piston row (15) or the pressure medium delivered by both piston rows (7, 15) is supplied to the consumer (2) as required.

14. The method according to claim 12 or 13, It is characterized in that The volume of pressure medium delivered by the piston row (7) when the eccentric shaft rotates is different from the volume delivered by the other piston row (15), and / or the pressure of the pressure medium originating from the piston row (7) is different from the pressure of the pressure medium originating from the other piston row (15).

15. The method according to claim 12, 13 or 14, It is characterized in that When the radial piston pump (1) is operated, the pressure medium delivered by the piston row (7) is supplied to a first consumer (2) and the pressure medium delivered by the other piston row (15) is supplied to a second consumer (22), the first consumer (2) being a first steerable wheel axle of a multi-purpose vehicle and the second consumer (22) being a second steerable wheel axle of a multi-purpose vehicle, wherein preferably, the radial piston pump (1) is configured as an emergency steering pump, wherein the first consumer (2) is a wheel steering gear or a steering cylinder of a steering system of the first wheel axle, and the second consumer (22) is a wheel steering gear or a steering cylinder of a steering system of the second wheel axle.

16. A steering system (24) for a vehicle, in particular for a multi-purpose vehicle, the steering system having at least two steerable axles, each of which can be deflected by an electric steering device and / or a hydraulic steering device in normal operation, and the steering system also having an emergency steering pump, the emergency steering pump being configured as a radial piston pump (1) according to any one of claims 1 to 11 or being operated by a method according to any one of claims 12 to 15, wherein A pressure line is provided for supplying the pressure medium delivered by the piston row (7) to the wheel steering gear or the steering cylinder of the steering device of the first wheel axle, and a further pressure line is provided for supplying the pressure medium delivered by the further piston row (15) to the wheel steering gear or the steering cylinder of the steering device of the second wheel axle.

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