THROTTLE VALVE ARRANGEMENT FOR HYDROSTATIC UNITS

Abstract

Throttle valve arrangement (1) for hydrostatic units, comprising: A) a valve housing (5) with a through-bore (6) defining an axial direction (10) of the throttle valve arrangement (1), and with an undercut (30) delimited by two end walls (25); B) a cylindrical bushing (35) inserted into the through-bore (6) such that the undercut (30) forms a flow chamber (32) in the valve housing (5) radially outside the bushing (35), wherein the axial openings of the bushing form an inlet opening (20) and an outlet opening (15) of the throttle valve arrangement (1), and the bushing (35) further comprises radially oriented inlet openings (36) and outlet openings (37) arranged at the respective end portions of the bushing (35) to enable fluid communication between the inlet opening (20) and the outlet opening (15) via the flow chamber (32); C) an axially movable elastic valve body (40) which: (i) when no or balanced hydraulic forces are applied to the inlet opening (20) and the outlet opening (15), is pretensioned by a closing spring (65) into an initial position in which the elastic valve body (40) closes the inlet openings (36) in the sleeve (35), (ii) when the hydraulic forces at the inlet opening (20) are greater than at the outlet opening (15), can be moved against the force of the closing spring (65) into a throttle valve opening position in which the inlet openings (36) in the sleeve (35) are open and a hydraulic flow from the inlet opening (20) via the flow chamber (32) to the outlet opening (15) is possible, and (iii) when the hydraulic forces at the outlet opening (15) are greater than at the inlet opening (20), is in the initial position and is designed to expand in the axial direction against the force of a dynamic pressure spring (55) in order to at least partially open the inlet openings (36) in the sleeve (35) and to enable a throttled hydraulic flow from the outlet opening (15) via the flow chamber (32) to the inlet opening (20).

Description

[0001] The invention relates to valves for hydrostatic adjustment units, in particular throttle valves for hydrostatic adjustment units, in particular hydrostatic axial piston units.

[0002] In the technical field of hydraulics, valves are used in many different applications, e.g. for throttling fluid flows in hydrostatic control units. For example, throttle valves are often used in axial piston units in engine operation to keep the pressure level on the outlet side above a lower limit. This is particularly true when the axial piston units are operated in an open circuit. Generally, throttle valves are used in situations where free, uncontrolled release / emptying of hydraulic fluid should not occur, as is often the case when a pressure potential should not be freely released. For example,The low-pressure side of a hydraulic power unit in a closed-circuit application should not be flushed into a tank or reservoir at maximum pressure for regeneration, cooling and / or refreshment, as a hard jet would create turbulence and gas bubbles in the reservoir, hindering cooling and / or regeneration of the hydraulic fluid.

[0003] Those skilled in the art are familiar with a variety of applications in which throttle valves for hydraulic or gaseous fluids can be used. All of these applications are covered by the present invention. For illustrative purposes, the invention is explained using the application described below for hydraulic axial piston units, which are operated, for example, in an open hydraulic circuit.

[0004] Axial piston units typically have a rotating cylinder block in which cylinder bores are arranged. Each cylinder bore accommodates a reciprocating displacer piston, so that a pressure chamber is enclosed between the displacer piston and the cylinder bore. There are two basic design principles of hydrostatic axial piston units: swash plate units, which have a tiltable swash plate on which the displacer pistons can slide as the pistons rotate together with the cylinder block. In the other design type – bent axis units – a centerline of the cylinder block can be tilted relative to a centerline of a rotating shaft. Regardless of the specific design, the pistons are pressed against a sliding surface by the hydraulic pressure in the pressure chambers.

[0005] The pressure in one or more pressure chambers may be low, e.g. because the pressure chambers are connected to an outlet of the hydraulic unit, e.g. to a tank or reservoir of an open hydraulic circuit. In this case, kinematic forces can cause the displacer pistons to lift off the sliding surface, as the low hydraulic pressure in the pressure chambers may not be high enough or sufficient counterforce cannot be generated against the kinematic forces to prevent the displacer pistons and / or their guide shoes from lifting off the sliding surface. This lifting not only leads to poor operating behavior of the hydraulic unit, such as noise generation and severe wear of components, but in the worst case can also lead to the destruction of the hydraulic unit.

[0006] To prevent lift-off, a throttle device can be provided in the outlet line of the hydrostatic unit to keep the pressure in the outlet line / channel above a required minimum reference pressure and to generate a (counter) force on the displacer pistons to maintain contact with the sliding surface.

[0007] However, a problem arises when the direction of fluid flow through the hydraulic system's lines is required to be reversible / bidirectional—that is, when the output is to become the input and vice versa, as in the case of reversible hydraulic motors. However, the hydraulic flow through an input line must not be throttled, as this would result in a loss of efficiency. Furthermore, minimizing the dimensions of hydraulic units is a constant challenge to increase design freedom and reduce the overall dimensions of the hydrostatic unit / system.

[0008] There are technical solutions available on the market to solve the problem described. These designs typically involve valves mounted on the connections of hydraulic power units and are usually designed as poppet valves or seat valves. The arrangement and distance of the connections to the pressure chambers, as well as the periphery of the hydraulic application, limit the available installation space and thus the flow rate of these throttle valve solutions, which are well known from technology. Throttle devices must provide a low pressure drop and a high flow rate / flow capacity when filling / feeding pressure chambers, but also a high flow rate / flow capacity when draining / emptying the pressure chamber above a specified minimum low pressure to avoid a reduction in the efficiency of the hydraulic power unit.At the same time, the throttle valve / throttle device should take up as little space as possible in order to be suitable for a wide range of hydraulic devices, for example.

[0009] US 2 555 334 A shows a hydraulic surge protection valve for the alternate release of a flow cross-section in two directions with a slide that can be axially displaced against different spring forces, whereby the spring forces act on opposite end faces of the slide to achieve different opening pressures.

[0010] DE 33 43 960 A1 describes a flow-limiting valve designed to ensure a load-independent flow rate under the influence of external forces on consumers subjected to one-sided external forces. While the system operates against the external forces, the flow through the flow-limiting valve remains essentially unaffected. For this purpose, a bypass with a check valve is provided, bypassing a metering orifice of the flow-limiting valve.

[0011] It is therefore an object of the invention to provide a throttle valve design for hydraulic power units that is capable of throttling a fluid flow between a higher pressure level and a lower pressure level in only one direction. The fluid flow should not be throttled in the other direction, and the flow resistance through the throttle valve in the filling direction should be as low as possible. At the same time, it is important that the throttle valve / throttle device has small dimensions and requires minimal installation space in a hydrostatic system / hydrostatic unit.

[0012] Even if described above in connection with axial piston units, the application of throttle valves, in particular throttle valves according to the invention, is not limited to the application in axial piston units described above and can also be used in connection with other types of hydraulic systems / units.

[0013] The object is achieved by a throttle valve arrangement according to claim 1. Preferred embodiments are described in the dependent subclaims.

[0014] A throttle valve arrangement according to the invention for hydrostatic units is designed as a slide valve and has a valve housing with a through-bore that defines an axial direction of the throttle valve. One of the two axial openings of the through-bore forms an inlet opening of the throttle valve, and the other opening forms an outlet opening. Between the inlet opening and the outlet opening, an undercut is formed in the valve housing, which is delimited in the axial direction by two end walls on either side. Depending on the manufacturing process selected for the throttle valve and the operational requirements of the throttle valve, the end walls can be formed integrally with the valve housing, which leads to high mechanical stability of the valve.Alternatively, the end walls can also be attached to the valve body as separate parts, which allows manufacturing alternatives for the valve body and the other components of the throttle valve assembly.

[0015] A cylindrical bushing is inserted into the through-bore and can be fastened to the end walls, e.g. by pressing in. Outside or radially outside the bushing, the undercut forms a flow channel in the housing. The flow channel is limited in the axial direction by the two end walls and is formed in the radial direction between the outer surface of the bushing and the inner surface of the undercut. The bushing has axial openings that form or are connected to the outlet port and the inlet port of the throttle valve. The bushing further has radially aligned openings on the inlet side and radially aligned openings on the outlet side, all arranged at the respective end sections of the bushing, in order to enable a fluid channel between the inlet port and the outlet port of the valve housing via the flow chamber formed by the undercut and the bushing. This means, e.g.that hydraulic fluid can enter the valve housing via the inlet at the inlet opening and be guided through the inlet-side radial openings in the bushing into the flow space outside / radially outside the bushing, from where it can re-enter the bushing via the outlet-side radial openings in the bushing and be guided to the outlet side / opening of the throttle valve. In general, and according to the invention, this flow path is also possible in reverse, i.e., from the outlet opening to the inlet opening.

[0016] An axially movable, elastic valve body assembly is arranged between the inlet and outlet openings at the end sections of the sleeve. The assembly has a hollow sliding element that is sealed and slidably guided within the sleeve. The general operation of a throttle valve assembly according to the invention is as follows: The elastic valve body of the throttle valve according to the invention is held in its initial position by a closing spring, in which no external forces act on the throttle valve assembly. In this position, the radial openings formed in the elastic valve body and the radially aligned openings of the inlet opening in the sleeve do not overlap, so that flow via the flow chamber formed radially outside the sleeve is prevented. The radial openings in the sleeve on the outlet side are open. This means that the throttle valve assembly according to the invention is closed in the initial position of the elastic valve body.

[0017] When a force occurs on the inlet side, the axially movable, elastic valve body is moved towards the pressure side against the force of the closing spring, whereby the radially aligned openings of the elastic valve body and the inlet-side bushing are brought into maximum overlap, i.e. the smallest possible flow restriction from the inlet to the pressure side is enabled. Here too, the radial openings in the pressure side bushing are constantly open. When a force occurs on the inlet side, the axially movable, elastic valve body is moved towards the pressure side against the force of the closing spring, whereby the radially aligned openings of the elastic valve body and the inlet-side bushing are brought into maximum overlap, i.e. the smallest possible flow restriction from the inlet to the pressure side is enabled. Here too, the radial openings in the pressure side bushing are constantly open.

[0018] When a force acts on the outlet side, the closing spring moves the elastic valve body towards the inlet side, i.e. essentially to its initial position. In addition, the compressive force on the outlet side also acts on a bottom region of the elastic valve body and can compress the dynamic pressure spring if the force generated by the pressure is large enough. By compressing the dynamic pressure spring, the radially aligned openings in the elastic valve body are brought into at least partial overlap with the radially aligned openings in the bushing at the inlet end as the elastic valve body expands in the axial direction. By expanding the elastic valve body in the axial direction, the flow path via the flow chamber is released because the radial openings in the outlet side bushing are constantly open and fluid can enter the flow channel.This enables a discharge flow with back pressure functionality, i.e. maintaining a back pressure during the discharge flow.

[0019] In general, the elastic valve body can be subjected to a compressive force on both sides, the inlet pressure side and the outlet pressure side, whereby the travel of the elastic valve body is limited, for example, by end stops depending on the position and axial width of the radial openings in the bushing and in the valve body itself. One end stop is reached when all radial openings on the inlet opening side are fully open or overlap, i.e. in the inlet position. The other end stop is reached when all radial openings on the inlet side are closed, i.e. in the initial position with the elastic valve body not expanded, i.e. when the dynamic pressure force is less than the force of the dynamic pressure spring.

[0020] In a preferred embodiment of the invention, the radial openings on the outlet side of the bushing are open in any position of the elastic valve body, and the end stops for limiting the travel path of the elastic valve body are formed by a through-bore extended in the axial direction through the elastic valve body, wherein the through-bore is penetrated by a pin or the like which is stationary with the bushing.

[0021] In a further preferred embodiment, the elastic valve body has a sliding element with a substantially cup-shaped cross-section, i.e., it has a hollow cylindrical shape, wherein one side of the cylindrical shape—the side facing the outlet end of the bushing—is closed by a bottom surface. On the cylindrical part, preferably on the inlet-side end section, the hollow sliding element has radially aligned openings that can be brought into an overlapping position with the radially aligned openings on the inlet side of the bushing.

[0022] The axially movable, elastic valve body further comprises a spring seat element with a T-shaped cross-section, which is guided for axial movement by the sliding element. A head region of the T- or mushroom-shaped spring seat element, i.e. a region with a larger diameter, is oriented towards the inlet opening and preferably seals with its circumferential outer surface against the inner surface of the sliding element. A stem region with a smaller diameter compared to the head region protrudes through the bottom surface / region of the sliding element. For this reason, a hole is provided in the bottom surface of the cup-shaped sliding element. The stem region does not necessarily form a fluid-tight connection with the bottom region of the sliding element.

[0023] In the elastic valve body assembly, a dynamic pressure spring is preloaded around the stem portion between the head portion of the mushroom-shaped spring seat element and the base of the cup-shaped sliding element. A locking element, e.g., a retaining ring, on the protruding portion of the stem limits the travel of the spring seat element relative to the sliding element in the expansion direction of the dynamic pressure spring, i.e., toward the inlet opening of the throttle valve housing. The stem portion of the spring seat element further has an axial blind hole and a radially arranged elongated hole through which a pin passes, holding the stem portion fixed relative to the bushing.A closing spring housed in the blind hole is pre-tensioned between the pin attached to the bushing and the spring seat element and thereby presses the elastic valve body group in the direction of the inlet opening, whereby the elongated hole in the shaft limits the axial travel of the elastic valve body within the bushing.

[0024] Preferably, the compliance of the closing spring is greater than the compliance of the dynamic pressure spring. In other words, less force is required to compress the closing spring than to compress the dynamic pressure spring. The force of the closing spring represents the opening force of the throttle valve on the inlet side, i.e., in the non-throttle direction. The dynamic pressure spring, on the other hand, represents the opening force of the throttle valve in the throttle direction, i.e., the force of the dynamic pressure spring determines the dynamic pressure in hydraulic lines that can be connected to the outlet side of the throttle valve according to the invention.

[0025] In order to enable the unrestricted inlet and the restricted outlet function, the bushing preferably has two rows of radially aligned inlet openings on the inlet side, wherein preferably both rows are used for the inlet function and only one row is used for the outlet function with back pressure holding function.

[0026] In particular, when no or balanced hydraulic forces act on the inlet and outlet sides of the throttle valve, the closing spring—preloaded in the blind bore of the stem of the spring seat element against the pin connecting the stem to the bushing—pressurizes the elastic valve body assembly toward the inlet opening into the throttle valve's initial position, in which all inlet-side radial openings in the bushing are closed by the sliding element, i.e., the respective radially aligned openings in the bushing and the sliding element do not overlap. Thus, the flow path via the flow chamber is closed, although the radial openings in the bushing on the outlet side remain open.

[0027] If the hydraulic forces at the inlet opening are greater than at the outlet opening, the closing spring is compressed until the pin in the elongated hole in the shaft of the sliding element limits the axial travel of the elastic valve body, in particular the shaft region of the spring seat element. According to the invention, the length and position of the elongated hole in the shaft region are determined such that the travel of the valve body in the direction of the inlet opening into an inlet position of the throttle valve arrangement ends at a position in which preferably all radial openings in the bushing on the inlet opening side are open and maximum flow from the inlet side to the outlet opening is possible via the flow chamber in the throttle valve housing. The hydraulic flow re-enters the bushing via the always open radial openings in the bushing on its outlet side.The radial openings at the outlet end of the bushing are preferably wider than those at the inlet-side end section, and preferably wider than both rows of the inlet-side opening together.

[0028] To achieve this inlet position of the throttle valve assembly according to the invention, only the force of the closing spring needs to be overcome. Therefore, the closing spring can be designed to be relatively weak or relatively flexible, since the function of the closing spring is merely to move the elastic valve body to its initial position when the throttle valve assembly is free from external forces.

[0029] If the hydraulic forces at the outlet port are greater than those at the inlet port, the elastic valve body with the sliding element is moved towards the inlet port until the pin in the elongated hole limits the movement. Furthermore, compressive forces act on the bottom region of the cup-shaped sliding element and can compress the dynamic pressure spring so that the axial length of the elastic valve body increases and the radial openings in the sliding element can at least partially overlap with at least one row of the radial openings in the bushing at its inlet-side end section. As a result, the stem region of the T-shaped spring seat element is held in its initial position by the pin, which passes through the axially elongated radial hole in the stem region and axially fixes the spring seat element to the bushing.From this explanation, the person skilled in the art will understand that the force of the dynamic pressure spring determines the dynamic pressure that can be maintained by the throttle valve arrangement according to the invention in the hydraulic system, e.g., on the outlet side of a hydraulic axial piston unit. When the dynamic pressure on the outlet side drops below the force of the dynamic pressure spring, the sliding element of the elastic valve body is moved by the dynamic pressure spring toward the pressure-free starting position, thereby closing the throttle valve arrangement.

[0030] Preferably, the valve housing is a generally rotationally symmetrical cylindrical part, which is manufactured, for example, by turning, 3D milling, 3D printing or any other manufacturing method known to a person skilled in the art.

[0031] Preferably, the undercut in the valve housing also has a cylindrical shape, is arranged coaxially with a through-bore in the valve housing, and forms an annular chamber in the valve housing outside the bushing. This evenly distributes the flow of hydraulic fluid in the undercut and minimizes areas of increased pressure—e.g., areas where the flow of hydraulic fluid is impeded by the geometry. As one skilled in the art will recognize, rotationally symmetrical parts, especially cylindrically shaped parts, can be manufactured particularly well using the aforementioned manufacturing processes.

[0032] Preferably, the rotational position of the bushing relative to the elastic valve body remains fixed, which can be ensured by a pin-axial groove connection between these two parts, in particular with respect to the cylindrical part of the hollow sliding element, so that the radial openings in both parts can be brought into maximum overlap or closed position. To this end, the T-cross-section shaped spring seat element should also be secured against rotation, since such rotation could be transmitted to the cup-shaped sliding element, e.g. via the axial locking on the stem part. For this reason, the pin can have functional interaction with both the bushing and the valve housing. However, it is important that the elastic valve body, more precisely the spring seat element, is able to move in the axial direction relative to the bushing, even if the rotational position of the two parts relative to each other is fixed.

[0033] In one embodiment of the invention, the assembly of bushing and elastic valve body can rotate inside the valve housing if the undercut is cylindrical.

[0034] In a further preferred embodiment, the pin can also be fastened to the valve housing, thereby fixing the rotational position of the bushing relative to the valve housing and thus also the rotational position of the elastic valve body. Depending on the type of functional connection between the pin and the bushing, the pin can also fix the translational position in the axial direction of the bushing relative to the valve housing. However, the translational position can also be fixed by pressing the bushing against a shoulder in the housing, e.g., by pressing, welding, soldering, or gluing the bushing into the valve housing.

[0035] In a further embodiment of the invention, the cup-shaped sliding element has a stepped shape with a smaller diameter on the outlet side. Such a design is advantageous when a relatively long dynamic pressure spring is to be used, since the cylindrical part of the sliding element should not overlap with the radial outlet openings in the outlet-side bushing when the throttle valve arrangement is in the fill / inlet position, i.e. the elastic valve body is in its initial position, in which the fluid flow from the inlet opening to the outlet opening is to be enabled with the least possible flow restrictions. Therefore, if relatively long dynamic pressure springs are to be used due to the spring force characteristics, a compromise must be found between the axial length of the valve housing and the cup-shaped sliding element.The use of a stepped design of the cup-shaped sliding element can be a design alternative, but makes the manufacturing of the cup-shaped sliding element more complicated.

[0036] The inlet-side radial openings and / or the outlet-side radial openings in the bushing and / or the radial openings in the sliding element can have a circular, elongated hole-like design or be designed as slots. All radial openings can be designed to be complementary to one another, i.e. they can / should be designed so that they completely overlap in the throttle valve inlet / opening / system filling position. At least the radial inlet openings in the bushing should be able to be fully opened so as not to form a bottleneck in the flow path. However, the openings in the bushing can also be shaped differently than the openings in the sliding element. Additionally or alternatively, the radial inlet openings on the inlet-opening side in the bushing and / or in the sliding element of the elastic valve body can have the same shape or a different shape than the openings on the outlet side of the bushing.

[0037] Preferably, the closing spring can be arranged in a blind bore in the shaft portion of the T-shaped spring seat element, through which a pin is guided in the radial direction, e.g., through a radial bore in the shaft portion or two elongated holes arranged opposite one another in the cylindrical surface of the shaft portion. On the side opposite the base of the blind bore, the closing spring is preferably supported on a slider that rests against the pin and is displaceable in the blind bore of the shaft.

[0038] The slide can, for example, be a rolling element guided in the blind bore in the shaft area of ​​the spring seat element. However, the slide can also be another component capable of reducing frictional forces when the valve switches between its positions or functions, i.e., when variable pressure forces act on the outlet side of the throttle valve assembly. For example, components with good sliding properties can also be provided by a specific friction-reducing material or coating to form the slide.

[0039] The valve body may have a plurality of axially aligned through holes and may be attached to hydraulic flanges, hydraulic hoses or hydraulic pipes, e.g. by means of bolts penetrating the through holes and cooperating with the device to which the valve body is to be attached.

[0040] The valve body may further comprise an O-ring groove on the inlet and / or outlet side of the body for receiving an O-ring capable of sealing the throttle valve assembly against other components of a hydraulic or hydrostatic unit / system to which the throttle valve may be connected. Once the throttle valve is attached to one of the above-mentioned components or to another component of a hydrostatic unit, the force pressing the throttle valve body against the component deforms the O-ring installed in the groove, creating a fluid-tight connection. Additionally, the connection may be suitable for fixing the longitudinal position of the bushing relative to the throttle valve body, e.g., when the additional component is in contact with the bushing, thereby forcing the bushing against a shoulder in the throttle valve body.

[0041] With reference to the attached figures, preferred embodiments of the throttle valve assembly according to the invention are explained in more detail to improve understanding of the underlying inventive concept. The present embodiments do not limit the scope of the inventive concept, but represent only one possible embodiment variant to which modifications may be made according to the knowledge of a person skilled in the art without departing from the scope of the invention. Therefore, all such modifications and changes are covered by the claimed invention. The figures show: Fig. 1 a sectional view of a preferred embodiment of the throttle valve arrangement according to the invention in a first position; Fig. 2 a sectional view of the embodiment of Fig. 1 in a second position; Fig. 3 a sectional view of the embodiment of Fig. 1 in a third position; Fig. 4 a sectional view of the embodiment of Fig. 1 in a fourth position; Fig. 5 the embodiment of Fig. 1 in a plan view of the outlet side;

[0042] The Fig. 1 to 5 show a preferred embodiment of the throttle valve assembly according to the invention, wherein like reference numerals refer to like parts. All sectional views of the Fig. 1 to 4 are made along the cutting plane, which in Fig. 5 is marked with the line AA.

[0043] The preferred embodiment is shown in three different printing situations, where Fig. shows the preferred embodiment of the throttle valve arrangement according to the invention in its initial position, in which no or a balanced pressure acts on both sides of the throttle valve. In Fig. The inlet or inlet situation is shown, where the pressure at the inlet opening 20 is higher than that at the outlet opening 15. A liquid flow from the inlet opening 20 to the outlet opening 15 is indicated by arrows. In the Fig. the pressure situation is reversed, ie the pressure at the outlet opening 15 is higher than at the inlet opening 20. The preferred embodiment for a throttle valve according to the invention is here in its throttle function position, in which a liquid flow - indicated by the arrows - from the outlet opening 15 to the inlet opening 20 is possible. Fig. The arrangement shown represents an intermediate position. The arrangement of Fig. 4 shows the fully open throttle position of a throttle valve according to the invention.

[0044] Fig. 1 shows a sectional view of a preferred embodiment of the throttle valve arrangement 1 according to the invention, which has a valve housing 5 with a through-bore 6, which defines an axial direction 10. For illustrative purposes only, the left opening of the through-bore 6 is shown in the Fig. 1 to 4 is referred to as the inlet opening 20 and the right-hand opening as the outlet opening 15. The inlet opening 20 can be connected, for example, to a pressure source if the throttle valve arrangement 1 is arranged according to the attached Fig. 1 to 4 from left to right, e.g. when pressure chambers of an axial piston unit are to be filled with pressurized liquid. In this case, the inlet opening 20 forms the inlet for the throttle valve arrangement 1 according to the invention. In the other case, e.g. when liquid is to be drained from the pressure chambers of an axial piston unit, the outlet opening 15 forms the inlet for the throttle valve arrangement 1 according to the invention, since the flow direction according to the attached Fig. 1 to 4 would run from right to left, ie from the outlet opening 15 to the inlet opening 20.

[0045] Coaxial to the axial direction 10 of the valve housing 5, a bushing 35 is inserted into the through-bore 6, which bushing, together with an undercut 30 formed in the valve housing 5, forms a flow chamber 32, which in a preferred embodiment is a flow chamber 32 outside the bushing 35, ie radially outside the bushing 35. Radial openings 36 and 37 are formed on the bushing 35 at the respective end sections, wherein in the embodiment of the Fig. 1 to 4 on the side of the inlet opening 20 of the throttle valve arrangement 1 two rows of slot-shaped inlet openings 36 and on the side of the outlet opening 15 only one row of axially wider outlet openings 37 are formed.

[0046] As a person skilled in the art knows, these radial (inlet or outlet) openings 36 and 37 can be designed in a wide variety of ways without departing from the essence of the invention. The designation radial inlet opening 36 and radial outlet opening 37 arises solely from their respective proximity to the inlet opening 20 and the outlet opening 15. All radial (inlet or outlet) openings 36 and 37 as well as the connections 15 and 20 can be flowed through by liquid in both directions. In general, the throttle valve arrangement according to the invention enables a liquid flow from the left opening designated by the reference number 20 to the right opening designated by the reference number 15 when a fluid under pressure from a source flows into the inlet opening 20 of the throttle valve arrangement 1 according to the invention on the left side of the Fig. 1 to 4 and leaves the throttle valve arrangement 1 according to the invention at the outlet opening 15. In the other direction, the throttle valve arrangement 1 according to the invention represents a flow resistance for a fluid flow from the right side of the Fig. 1 to 4 towards the left side in order to generate and maintain a desired back pressure in the system, which is applied to the right side of the throttle valve arrangement 1 according to the invention.

[0047] An elastic valve body 40 is inserted into the bushing 35, which has a hollow sliding element 45, a spring seat element 50 with a T-shaped cross-section, and a dynamic pressure spring 55. The hollow sliding element 45 has a cup-shaped cross-section, wherein the cylindrical part 48 has radially aligned openings 46 and seals with the inner surface of the bushing 35. The bottom area 47 serves as a spring seat for the dynamic pressure spring 55. The radially aligned openings 46 in the cylindrical part 48 of the hollow sliding element 45 can be brought into an overlapping position with at least one row of the radial filling openings 36 in the bushing 35 (see also Fig. 2, Fig. 3 and Fig. 4).

[0048] The elastic valve body 40 can move axially relative to the bushing 35 as an assembly, i.e., the hollow sliding element 45 can move together with the spring seat element 50. Relative movement of these two parts, i.e., the spring seat element 50 and the hollow sliding element 45, is only elastically possible when the dynamic pressure spring 55 is compressed. For this purpose, the dynamic pressure spring 55 is mounted in a preloaded manner between a head region 51 of the spring seat element 50 with a T-shaped cross-section and the base region 47 of the sliding element 45. This assembly / subassembly is held together by a securing element 57 around the shaft region 52 of the sliding element 45, e.g., a retaining ring.

[0049] The axial travel of the valve body 45 is limited by a pin 60, which is housed in an elongated, radial slot 53 in the shaft region 52. Furthermore, a blind hole 54 is provided in the shaft region 52 for receiving a closing spring 65, which is preloaded between the dead end of the blind hole 54 and the pin 60, which traverses the slot 53 in the shaft region 52. Therefore, the T-shaped or mushroom-shaped spring seat element 50 can move elastically within the limits predetermined by the axial length of the slot 53 and transmits this movement (elastically) to the sliding element 45 via the dynamic pressure spring 55 and the securing element 57.

[0050] The pin 60 connects / holds the spring seat element 50 within the bushing 35 because the pin 60 extends radially through the shaft portion 52 and is secured at both ends to the bushing 35. In a further embodiment of the invention, the pin 60 can be extended toward the valve housing 5 and thereby effect not only the angular position of the valve body 40 relative to the bushing 35, but also the angular position of the bushing 35 relative to the valve housing 5. Preferably, a pin or a rolling element 70, which is arranged between the bushing 35 and the cylindrical part 48 of the hollow sliding element 45 and can run / slide in a groove 75 located in one of these two parts, can establish the angular position between the bushing 35 and the valve housing 40.

[0051] In a preferred embodiment, a slider 62 is arranged in the blind hole 54 of the shaft region 52 between the closing spring 65 and the pin 60, which serves as a movable spring seat for the closing spring 65.

[0052] Fig. 1 shows the preferred embodiment of a throttle valve arrangement 1 according to the invention in the initial position without or with balanced pressure at the inlet opening 20 and at the outlet opening 15. The closing spring 65 presses the slide 62 against the pin 60, whereby the elastic valve body 40 in Fig. is moved to the left. The pin 60 limits the movement because the pin 60 abuts the right end of the elongated hole 53 in the shaft region 52 of the spring seat element 50. In this position of the elastic valve body 40, the inlet openings 36 of the bushing 35 are closed by the cylindrical part 48 of the sliding element 45. At the same time, the radial openings 46 in the cylindrical part 48 of the sliding element 45 are closed by the bushing 35. Thus, fluid flow in both directions is prevented because all radial openings on the inlet side of the throttle valve arrangement 1 according to the invention are closed. Furthermore, the dynamic pressure spring 55 is not compressed more than specified in the design phase, which can be seen from the fact that the bottom region 47 of the sliding element 45 rests against the securing element 57, a snap ring in this embodiment.

[0053] Fig. 2 shows the throttle valve arrangement 1 according to the invention in the open / inlet position, ie in a position in which the pressure forces at the inlet opening 20 are higher than at the outlet opening 15. As a result, the head region 51 of the spring seat element 50 presses the elastic valve body 40 towards the outlet opening 15 until the pin 60 rests in the elongated hole 53 facing the inlet opening 20, which limits the axial movement of the elastic valve body 40. As can be seen from Fig. As can be seen, in this situation, i.e. in this position of the elastic valve body 45 or the sliding element 45, both rows of radial inlet openings 36 in the bushing 35 are open, the second, further inner row overlapping with the radial openings 46 in the sliding element 45. This enables, as indicated by the arrows, a fluid flow from the inlet opening 20 via the flow chamber 32 to the outlet opening 15, with all possible openings 36 and 46 being fully open and the lowest possible flow resistance being achieved. In order to bring the throttle valve arrangement 1 according to the invention into this position, only the force of the closing spring has to be overcome, which can be relatively small, since the function of the closing spring is to close the throttle valve arrangement 1 according to the invention when there is no pressure or a balanced pressure at the inlet opening 20 and the outlet opening 15.This means that the closing spring 65 must generate a valve closing force sufficient to move the elastic valve body 40 when no external forces act on the elastic valve body 40. Accordingly, this valve closing force can be relatively small.

[0054] Fig. 3 shows the throttle valve arrangement 1 according to the invention in an intermediate position, i.e. in a position in which the pressure forces at the outlet opening 15 are higher than at the inlet opening 20, but the force difference between the forces at the outlet opening 15 and the inlet opening 20 is relatively small. Therefore, pressure forces act on the front of the shaft region 52 and on the slide 62. If the fluid chambers on both sides of the slide 62 were fluidically separated, these pressure forces would compress the closing spring 65 and move the slide 62 into the blind hole 54. In the embodiment presented, however, the fluid chambers on both sides of the slide 62 are connected to one another. Therefore, there is no pressure difference across the slide 62 and the slide 62 is held in contact with the pin 60 by the closing spring 65.The fluid connection between the fluid chambers on both sides of the slide can be established, for example, by a corresponding tolerance of the slide or by a through-bore either in the slide or in the shaft region 52. Both forces move the sliding element 45 in the direction of the inlet opening 20 of the throttle valve arrangement 1. In addition, the compressive forces also act on the outer surface of the base region 47 of the sliding element 45, whereby the dynamic pressure spring 55 is compressed and the sliding element 45 is lifted off the securing element 57 on the shaft region 52. The overall axial length of the elastic valve body 40 is thus resiliently / elastically increased and the radial openings 46 in the sliding element 45 at least partially overlap with the radial fill openings 36 in the bushing 35. In the illustrated embodiment of the . Fig. 3, the radial openings 46 partially overlap with the outer row of radial inlet openings 36. As indicated by the arrows, fluid flow is enabled from the outlet opening 15 to the inlet opening 20 via the flow chamber 32.

[0055] In Fig. 4 shows a fully open throttle position of the throttle valve assembly 1. Similar to the Fig. 3, the pressure forces at the outlet opening 15 are higher than at the inlet opening 20. Compared to the position shown in Fig. However, in the position shown in Figure 3, the difference between the pressure forces at the outlet opening 15 and the inlet opening 20 is higher than in the middle throttle valve position. This results in the dynamic pressure spring 55 being compressed more strongly and the elastic valve body 40 having a greater length than in the middle throttle valve position. This leads to a greater overlap of the radial openings 46 in the sliding element 45 with the inlet openings 36 in the bushing 35. A lower hydraulic resistance counteracts the hydraulic flow from the outlet opening 15 to the inlet opening 20. There are various design options for limiting the elastic expansion of the elastic valve body 40. As shown in Fig. 4, the slide 62 can rest against one end of the groove 75 and thereby limit the movement of the sliding element 45 relative to the bushing 35. Alternatively, the valve housing 5 or an additional part attached to the valve housing can have a shoulder in the region of the inlet opening 20, against which the sliding element 45 can be pressed by the resulting pressure force when the throttle valve 1 is in its fully open throttle function position.

[0056] From the Fig. 3 or Fig. 4 and the fully open throttle (end) position of the throttle valve arrangement 1 according to the invention, it can be seen that when there is a pressure drop at the outlet opening 15, the compressed dynamic pressure spring 55 initially gives way and pushes the sliding element 45 in the direction of the outlet opening 15 until the sliding element 45 rests against the securing element 57. As a result, the radial openings 46 in the sliding element 45 are displaced and the radial openings 46 in the sliding element 45 are closed. Since the overlap with the radial openings 36 in the bushing 35 no longer occurs, the fluid flow is thus interrupted.

[0057] Fig. Figure 5 shows a plan view of the outlet side of the throttle valve assembly 1 according to the invention. The valve housing 5 has axially aligned holes 85 for fastening the throttle valve assembly 1 to other hydraulic components, wherein an O-ring is inserted into the O-ring groove 7 (see Fig. 1 to 4) can be used to seal the valve housing 5 against the other components. In this embodiment, four mounting holes 85 are provided. However, this number can be increased or decreased depending on the design and application requirements and the knowledge of a person skilled in the art.

[0058] In the Fig. In the central part of the throttle valve assembly 1 shown in Figure 5, the pin 60 can be seen, which extends through the shaft portion 52 of the spring seat element 50 and ensures the angular position of the spring seat element 50 with respect to the valve housing 5. The pin 60 also limits the axial travel of the elastic valve body 40, as described above.

[0059] From the above disclosure and the accompanying figures as well as the claims, it is apparent that the throttle valve assembly 1 according to the invention offers many possibilities and advantages over the prior art. Those skilled in the art will further recognize that further modifications and changes can be made to the throttle valve assembly 1 according to the invention without departing from the spirit of the invention. Therefore, all such modifications and changes fall within the scope of the claims and are covered by them. It should be further understood that the examples and embodiments described above are for illustrative purposes only and that various modifications, changes, or combinations of embodiments that would be apparent to one skilled in the art are within the spirit and scope of this application. List of reference symbols 1 throttle valve arrangement 5 valve housing 6 through hole 7 O-ring groove 10 Axial direction 15 Outlet opening 20 Inlet opening 25 front wall 30 undercut 32 Flow space 35 socket 36 Inlet opening 37 Outlet opening 40 Elastic valve body 45 Sliding element 46 Radial opening 47 Floor area 48 Cylindrical part 50 spring seat element 51 Head area 52 shaft area 53 slot 54 blind hole 55 dynamic pressure spring 57 Securing element 60 pen 62 sliders 65 closing spring 70 rolling elements 75 groove 85 Hole / Mounting hole

Claims

[1] Throttle valve arrangement (1) for hydrostatic units, comprising: A) a valve housing (5) with a through-bore (6) defining an axial direction (10) of the throttle valve arrangement (1), and with an undercut (30) delimited by two end walls (25); B) a cylindrical bushing (35) inserted into the through-bore (6) such that the undercut (30) forms a flow chamber (32) in the valve housing (5) radially outside the bushing (35), wherein the axial openings of the bushing form an inlet opening (20) and an outlet opening (15) of the throttle valve arrangement (1), and the bushing (35) further comprises radially oriented inlet openings (36) and outlet openings (37) arranged at the respective end portions of the bushing (35) to enable fluid communication between the inlet opening (20) and the outlet opening (15) via the flow chamber (32); C) an axially movable elastic valve body (40) which: (i) when no or balanced hydraulic forces are applied to the inlet opening (20) and the outlet opening (15), is pretensioned by a closing spring (65) into an initial position in which the elastic valve body (40) closes the inlet openings (36) in the sleeve (35), (ii) when the hydraulic forces at the inlet opening (20) are greater than at the outlet opening (15), can be moved against the force of the closing spring (65) into a throttle valve opening position in which the inlet openings (36) in the sleeve (35) are open and a hydraulic flow from the inlet opening (20) via the flow chamber (32) to the outlet opening (15) is possible, and (iii) when the hydraulic forces at the outlet opening (15) are greater than at the inlet opening (20), is in the initial position and is designed to expand in the axial direction against the force of a dynamic pressure spring (55) in order to at least partially open the inlet openings (36) in the sleeve (35) and to enable a throttled hydraulic flow from the outlet opening (15) via the flow chamber (32) to the inlet opening (20). [2] Throttle valve assembly (1) according to claim 1, wherein the axially movable elastic valve body (40) comprises: i) a hollow sliding element (45) which can be slidably guided in a sealed manner by the bushing (35) in the axial direction (10) and has a substantially cup-shaped cross-section; ii) a spring seat element (50) with a T-shaped cross-section, which is guided axially movably by the sliding element (45), wherein a head region (51) is aligned in the direction of the inlet opening (20) and seals with the inner surface of the sliding element (45), and wherein a shaft region (52) projects through a bottom region (47) of the sliding element (45) in the direction of the outlet opening (15), iii) the dynamic pressure spring (55) which is prestressed around the shaft region (52) between the head region (51) and the bottom region (47) of the sliding element (45), wherein a securing element (57) on the projecting part of the shaft region (52) limits the travel path of the spring seat element (50) relative to the sliding element (45) in the expansion direction of the dynamic pressure spring (55); - wherein, when no or balanced hydraulic forces are applied to the inlet opening (20) and the outlet opening (15), the closing spring (65) bears against a pin (60) attached to the bushing (35) and presses the elastic valve body (40) via the spring seat element (50) in the direction of the inlet opening (20) into the initial position in which the inlet openings (36) in the bushing (35) are closed by the sliding element (45), - wherein, when the hydraulic forces at the inlet opening (20) are greater than at the outlet opening (15), the elastic valve body (40) is pressed towards the outlet opening (15) into the opening position of the throttle valve (1), in which all openings (36, 37) in the sleeve (35) are open, and the hydraulic flow from the inlet opening (20) to the outlet opening (15) is enabled; and - wherein, when the hydraulic forces at the outlet opening (15) are greater than at the inlet opening (20), the sliding element (45) is moved in the direction of the inlet opening (20), whereby the dynamic pressure spring (55) is compressed so that the radial openings (46) in the sliding element (45) at least partially overlap with the inlet openings (36) in the bushing (35) and a hydraulic flow from the outlet opening (15) to the inlet opening (20) is made possible. [3] Throttle valve assembly (1) according to claim 1 or 2, wherein the valve housing (5) is a generally cylindrical rotary member. [4] Throttle valve arrangement (1) according to one of claims 2 or 3, wherein the undercut (30) has a cylindrical shape and forms an annular flow chamber (32) in the valve housing (5) outside the bushing (35) coaxially with the through-bore (6). [5] Throttle valve arrangement (1) according to one of claims 2 to 4, wherein the pin (60) determines the relative angular position of the bushing (35) to the valve body (40). [6] Throttle valve arrangement (1) according to one of the preceding claims, wherein a rolling body (70) which is fastened to the sliding element (45) and is guided in an axially aligned groove (75) in the bushing (35), or which is fastened to the bushing (35) and is guided in an axially aligned groove (75) in the sliding element (45), determines the relative angular position of the sliding element (45) to the spring seat element (50) of the elastic valve body (40). [7] Throttle valve arrangement (1) according to one of claims 2 to 6, wherein the pin (60) is fixed to the valve housing (5). [8] Throttle valve arrangement (1) according to one of the preceding claims, wherein the sliding element (45) is step-shaped and has the smaller diameter on the side of the outlet opening (15). [9] Throttle valve arrangement (1) according to one of the preceding claims, wherein the inlet openings (36), the outlet openings (37) in the bushing (35) and / or the radial openings (46) in the sliding element (45) have a circular or elongated hole shape or are designed as slots. [10] Throttle valve arrangement (1) according to one of claims 2 to 9, wherein the closing spring (65) is arranged in an axial blind hole (54) in the shaft region (52), which has an axial elongated hole (53) through which the pin (60) radially penetrates the shaft region (52), and the closing spring (65) is supported on a slide (62) which bears against the pin (60). [11] Throttle valve arrangement (1) according to claim 10, wherein the slide (62) is guided in the blind hole (54) in the shaft region (52) of the spring seat element (50). [12] Throttle valve arrangement (1) according to one of the preceding claims, wherein the bushing (35) is fixed to the end walls (25) by pressing, welding, soldering and / or gluing. [13] Throttle valve arrangement (1) according to one of the preceding claims, wherein the valve housing (5) has a plurality of axially aligned mounting holes (85) with which the throttle valve arrangement (1) can be connected to hydraulic flanges, hydraulic hoses, hydraulic lines or other components of a hydraulic system. [14] Throttle valve assembly (1) according to any one of the preceding claims, wherein the valve housing (5) has an O-ring groove (7) on the inlet side and / or the outlet side to receive an O-ring suitable for sealing the throttle valve to hydraulic flanges, hydraulic hoses, hydraulic lines or other components of a hydraulic system. [15] Throttle valve arrangement (1) according to one of claims 13 or 14, wherein the bushing (35) is axially fixed with respect to the valve housing (5) when the valve housing (5) is attached to hydraulic flanges, to hydraulic hoses or to hydraulic lines or to other components of a hydraulic system.

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