HYDRAULIC SYSTEM WITH INERCY LOAD DAMPING AND CONTINUOUS OIL PREPARATION

Abstract

A hydraulic system is equipped with a pump that delivers pressurized hydraulic fluid through a primary supply line to a closed-center control valve. From the control valve, the fluid is routed through working lines to a hydraulic motor. The hydraulic fluid discharged by the hydraulic motor is routed through the control valve to an outlet line with a backpressure check valve set to a primary pressure. To keep the outlet line completely filled, a secondary supply line extends between the primary supply line and the outlet line. This secondary supply line is equipped with a pressure reducing valve set to a secondary pressure higher than the primary pressure of the backpressure check valve. An oil conditioning circuit for continuous hydraulic fluid conditioning is located between the backpressure check valve and a return reservoir.

Description

AREA

[0001] The present disclosure relates to hydraulic systems with inertial load damping and continuous oil conditioning. Although the examples described here are in connection with such hydraulic systems for work vehicles, it should be noted that the present disclosure has a broader scope, including applications for non-vehicle-related machinery applications. BACKGROUND

[0002] Hydraulic motors, in the form of rotary motors and linear hydraulic cylinders, are used to move large bodies, resulting in significant inertial forces. Mitigating these large inertial forces has been problematic, especially since the moving large bodies must be stopped quickly. Typically, when the load stops, the oil on one side of the motor is forced through a relief valve, while the oil on the other side of the motor experiences cavitation. Fluid is directed to the cavitation side through anti-cavitation valves. In some systems, the anti-cavitation valves may not supply enough fluid to the cavitation side of the motor, leading to noise and potential vibration of the load during stopping. Insufficient fluid supply to the cavitation side of the motor when the load is stopped also results in unnecessary heating of the hydraulic oil.

[0003] An example of a mechanism that can experience this cavitation problem is a hydraulic system that controls the swiveling motion of an excavator's cab and boom. Excavators are typically equipped with a swiveling boom attached to a cab section, which in turn is connected to the vehicle chassis via a swivel frame. The swivel frame has a vertical pivot axis for rotating the boom, which is mounted on the cab, around a vertical axis relative to the vehicle chassis. In applications of this type, the cavitation discussed above is generated, or occurs in some other way, when the cab and boom are swiveled and then quickly stopped. This causes a hydraulic motor coupled to the swivel frame to be driven in reverse. This heats the hydraulic oil, generates noise, and may cause vibrations in the boom and cab.These conditions are caused by the hydraulic rotary actuator's return fluid being forced under high pressure through the relief valves when the control valve closes with the center closed. Simultaneously, the supply side of the hydraulic rotary actuator experiences fluid loss or cavitation. The resulting high pressure on the return fluid side of the hydraulic rotary actuator now pushes the cab and boom back toward the cavitated side, building up pressure there. This newly generated pressure then pushes on the other side of the rotary actuator. This oscillating motion continues until the slewing energy is dissipated and the oscillation of the cab and boom ceases.

[0004] In addition to the unwanted noise and vibration caused by the cavitation problem described above, the design of typical hydraulic rotary motor circuits, which operate using anti-cavitation valves and closed-center control valves, limits the possibilities for hydraulic oil treatment, such as cooling and / or filtering. Hydraulic oil only flows through such systems when the hydraulic motor is running. However, while the hydraulic motor is inactive, no oil flows through the system, even if a source supplying the motor with pressurized hydraulic fluid, such as a variable displacement hydraulic pump, is actively operating.Therefore, oil conditioning devices located downstream of the closed-center control valve in an outlet line in such systems are completely ineffective in conditioning the fluid during periods of inactivity of the swivel motor. SUMMARY

[0005] This summary is provided to present a selection of concepts in simplified form, which are described in more detail below. This summary is not intended to identify key factors or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of protection of the claimed subject matter that can be operationally coupled with

[0006] The embodiments described herein are directed towards hydraulic systems that offer improved inertial load damping while ensuring continuous hydraulic oil conditioning.

[0007] According to one aspect, a hydraulic system is provided to dampen the high inertial forces generated by a body driven by a hydraulic motor. The hydraulic system includes a source of pressurized hydraulic fluid, a first supply line coupled to the source of pressurized hydraulic fluid, a control valve coupled to the first supply line, a working line coupling the control valve to the hydraulic motor, an outlet line coupled to the control valve, the outlet line being capable of returning outlet fluid via a return reservoir to the source of pressurized hydraulic fluid, a backpressure check valve located in the outlet line, the backpressure check valve being set to a first pressure head, and an anti-cavitation valve.The hydraulic system comprises an oil conditioning circuit located in the outlet line between the outlet line and the working line, an oil conditioning circuit situated in the outlet line between the backpressure check valve and the return reservoir, a second supply line extending between the first supply line and the outlet line, and a pressure reducing valve hydraulically positioned in the second supply line, the pressure reducing valve being set to a second pressure head. In the hydraulic system, the second pressure head of the pressure reducing valve is greater than the first pressure head of the backpressure check valve, allowing hydraulic fluid to flow through the oil conditioning circuit during operation of the pressurized hydraulic fluid source.

[0008] In one of the embodiments described here, the hydraulic system further includes a flow control orifice located in the second supply line, wherein the flow control orifice can be operated to control a flow rate of hydraulic fluid flowing through the second supply line and through the oil preparation circuit.

[0009] In one of the embodiments described here, the hydraulic system includes an oil preparation circuit which includes a fluid filter device located in the outlet line between the back pressure check valve and the return reservoir.

[0010] In one of the embodiments described here, the hydraulic system includes an oil preparation circuit which includes a fluid cooler device located in the outlet line between the back pressure check valve and the return reservoir.

[0011] In one of the embodiments described here, the hydraulic system further includes a cooler bypass check valve which is hydraulically coupled in parallel to the fluid cooler device, wherein the cooler bypass check valve provides a path through which hydraulic oil can bypass the filter device.

[0012] In one of the embodiments described here, the hydraulic system includes a cooler bypass check valve that is set to a pressure greater than the second pressure head of the pressure reducing valve.

[0013] In one of the embodiments described here, the source of the pressurized hydraulic fluid of the hydraulic system is a pump.

[0014] In one of the embodiments described here, the hydraulic system includes a control valve that comprises a valve with a closed center.

[0015] In one of the embodiments described here, the hydraulic system also includes a pressure relief valve mounted hydraulically parallel to the anti-cavitation valve.

[0016] In one of the embodiments described here, the hydraulic system includes a hydraulic motor which includes one or more hydraulic rotary motors and / or a double-acting hydraulic cylinder.

[0017] In one of the embodiments described here, the source of the hydraulic fluid for the hydraulic system includes a variable displacement pump.

[0018] To achieve the foregoing and related objectives, the following description and the attached drawings present certain illustrative aspects and implementations. However, these indicate only a few of the various ways in which one or more aspects may be implemented. Further aspects, advantages, and new features of the disclosure will become apparent from the following detailed description when considered in conjunction with the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are included in and form part of this document, depict embodiments of the disclosure which, together with the preceding general descriptions and the detailed description below, serve to illustrate the embodiments of this disclosure by way of example. Fig. Figure 1 is a side view of an implementation that includes a hydraulic system according to an exemplary embodiment. Fig. Figure 2 is a hydraulic diagram of a hydraulic system according to an exemplary embodiment. Fig. Figure 3 is a hydraulic diagram of a hydraulic system according to an exemplary embodiment. DETAILED DESCRIPTION

[0020] The claimed subject matter is now described with reference to the drawings, in which the same reference numerals are consistently used to refer to the same elements. For explanatory purposes, numerous specific details are set forth in the following description to provide a thorough understanding of the claimed subject matter. However, it may be apparent that the claimed subject matter can be practiced without these specific details. In other cases, structures and devices are shown in block diagram and / or schematic form to simplify the description of the claimed subject matter.

[0021] For a better understanding of the basic features of this disclosure, reference is made below to the embodiments described herein and illustrated in the drawings, and specific formulations are used to describe them. It should be noted, however, that this is not intended to limit the scope of protection of this disclosure, considering such changes and further modifications to the illustrated devices and methods, as well as further applications of the basic features of this disclosure, that would normally be apparent to a person skilled in the art in the field to which this disclosure relates.

[0022] The exemplary implementation is designed in an excavator 1, which is located in Fig. Figure 1 is shown in general terms. The excavator 1 includes a main body 10 with a driver's cab 12 at one end, which is mounted on a chassis 14 by means of a pivot axis 16. The body 10 can be rotated about a full circle relative to the chassis 14 on the pivot axis 16. The pivoting of the body is powered by a hydraulic motor 18 ( Fig. 2 and Fig. 3) is achieved, which drives a gear transmission (not shown) that can be engaged with a large ring gear (not shown) in the rotary mechanism to rotate the assembly 10.

[0023] The chassis 14 includes a pair of running chains 22 on opposite sides of the chassis, and the corresponding running chains are driven by hydraulic motors (not shown) through appropriate couplings (not shown) and reduction gears (not shown) in a known manner.

[0024] The excavator 1 includes a large boom 28 extending from the superstructure 10, which can be pivoted in a vertical arc by actuating a pair of boom cylinders 30. A dipper stick or arm 32 is pivotably mounted at the outer end of the boom, and its position is controlled by a hydraulic cylinder 34. At the lower end of the dipper stick or arm 32 is a conventional excavator bucket 36, which can be pivoted relative to the arm 32 by means of a hydraulic cylinder 38. All of the above represents more or less conventional designs. The control of the hydraulic motor 18 using a hydraulic system with inertial load damping according to one embodiment is described below, along with illustrations of the Fig. 2 and Fig. 3 described.

[0025] First on Fig. Referring to Section 2, a hydraulic system 100 includes a hydraulic motor 18, which serves to pivot the cabin 12 and the boom 28 relative to the supporting chassis 14 about a vertical axis defined by the vertical axis of rotation 16. The position of the cabin 12 and the boom 28 relative to the chassis 14 is controlled by a three-position control valve 40. The control valve 40 has a pivot position to the right, a pivot position to the left, and a stationary position. The control valve 40 is shown in its stationary position for illustration. Pressurized hydraulic fluid from a source 42 of the pressurized hydraulic fluid is coupled to the control valve 40 via a first supply line 44. In the illustrated embodiment, the source of the pressurized hydraulic fluid is a variable displacement pump, as shown schematically.The control valve 40 is hydraulically coupled to the hydraulic rotary actuator 18 via the first and second working lines 46 and 48. Pressurized and discharged hydraulic fluid passes through the working lines 46 and 48. Discharged hydraulic fluid from the rotary actuator 18 passes through the control valve 40 to the outlet line 50. The outlet line 50 is equipped with a backpressure check valve 52, which has a first pressure head. If the pressure falls below this first pressure head, the backpressure check valve 52 closes. If the pressure exceeds this first pressure head, the backpressure check valve 52 opens, and the hydraulic fluid is discharged back to the reservoir 54, where it is returned to the pump 42.

[0026] In one example, the backpressure check valve is set to 3 bar. When the pressure is below 3 bar, the backpressure check valve 52 is closed. When the pressure exceeds this initial pressure head of 3 bar, the backpressure check valve 52 opens, and the hydraulic fluid is discharged back to the reservoir 54, where it is returned to the pump 42.

[0027] Both sides of the rotary actuator 18 are also equipped with a pressure relief valve 56 and 58, as well as an anti-cavitation valve 60 and 62. The pressure relief valve 56 is coupled in parallel to the anti-cavitation valve 60. Both valves 56 and 60 are hydraulically positioned between the working line 46 and the outlet line 50. Similarly, the pressure relief valve 58 is coupled in parallel to the anti-cavitation valve 62. These two valves 58 and 62 are, in turn, hydraulically positioned between the working line 48 and the outlet line 50.

[0028] A second supply line 70, a pressure reducing valve 72, and a flow control orifice 74 are provided. The second supply line 70 extends between the first supply line 44 and the outlet line 50. The flow of the pressurized hydraulic fluid through this bypass path is controlled by the pressure reducing valve 72 and the flow control orifice 74. The pressure reducing valve 72 and the flow control orifice 74 are hydraulically positioned in the second supply line 70, and the pressure reducing valve 72 is set to a second pressure head that is related to the first pressure head of the backpressure check valve 52. In this embodiment, the pressure reducing valve 72 is set to a second pressure head that is greater than the first pressure head of the backpressure check valve 52.In this way, the hydraulic oil is continuously conditioned whenever the source of the pressurized hydraulic fluid 42 is activated by the flow of the fluid through an oil conditioning circuit 80, which is arranged between the backpressure check valve 52 and the reservoir 54. The flow control orifice 74 of the hydraulic system 100 is selected to control the flow rate of the hydraulic fluid through the second supply line 70 and thus also through the oil conditioning circuit 80, even when the three-position control valve 40 is in the stationary position shown. The flow control orifice 74 is provided to represent a controlled or otherwise adjusted flow limitation in the bypass path.

[0029] In one embodiment, the oil conditioning circuit 80 includes a fluid cooler 82 and a fluid filter 84. The fluid cooler and filter 82, 84 can be arranged in series between the backpressure check valve 52 and the reservoir 54. In this way, the hydraulic system 100 can be operated to advantageously condition the hydraulic fluid whenever the source of the pressurized hydraulic fluid 42 is activated, including during periods of inactivity of the rotary actuator, and also to quickly supply the hydraulic fluid to the cavitation side of the motor 18, thereby minimizing noise due to cavitation and thus also reducing the heating of the hydraulic oil.

[0030] In the hydraulic system 100 concerned, improved inertial load damping is ensured by the arrangement of the second supply line 70 and the pressure reducing valve 72 between the first supply line 44 and the outlet line 50. Continuous oil conditioning is also ensured in the circuit in question by setting the pressure reducing valve 72 to a second pressure head that is higher than the first pressure head of the backpressure check valve 52. The combination of improved inertial load damping and continuous oil conditioning advantageously contributes to reducing equipment failures and extends maintenance intervals, thereby achieving more efficient machine utilization.

[0031] In the example discussed above, the pressure reducing valve 72 is set to 7 bar and the backpressure check valve 52 to 3 bar. Therefore, the pressure reduction valve 72, set to 7 bar, is 4 bar higher than the 3 bar setting of the backpressure check valve 52. In this way, the outlet line 50 between the backpressure check valve 52 and the control valve 40 is maintained at a minimum pressure of 3 bar and a maximum pressure of 7 bar. Consequently, the backpressure at the anti-cavitation valves 60 and 62 in the outlet line 50 is at the same pressure level, and additional fluid can be directed from the outlet line 50 to the cavitation side of the hydraulic motor 18. The rapid supply of fluid to the cavitation side dampens the vibration when a large body is abruptly stopped.

[0032] Next up Fig. 3 Referring to Figure 3, a hydraulic system 100' includes a hydraulic motor 18 which can be operated to pivot the cabin 12 and the boom 28 relative to the supporting chassis 14 about a vertical axis defined by the vertical pivot axis 16. The hydraulic system 100' shown is identical in every respect to the one described in Figure 3. Fig.The hydraulic system 100 shown in Figure 2 is modified, but with the addition of a cooler bypass check valve 86. In the illustrated example, the cooler bypass check valve 86 is hydraulically coupled in parallel to the fluid cooler device 82. As shown, the cooler bypass check valve 86 provides a path by which hydraulic oil can bypass the filter device 82. In the illustrated embodiment, the cooler bypass check valve 86 is set to a higher pressure than the pressure reducing valve 72. In a particular embodiment, the cooler bypass check valve 86 is set to a pressure of approximately 8 bar. It should be noted that the cooler bypass check valve 86 is particularly advantageous during periods of operation in cold weather, even during times when operation of the hydraulic system 100 is required although the filter device 82 is overloaded, full, and / or clogged or damaged.

[0033] It is understood that other embodiments may be used and structural and functional modifications made without deviating from the scope of protection of the claims. The foregoing descriptions of embodiments are provided for illustrative and descriptive purposes. They do not claim to be exhaustive and do not limit the embodiments to the specific forms disclosed. Accordingly, many modifications and variations are possible in light of the foregoing teachings. It is therefore intended that the scope of protection of the claims is not limited by this detailed description.

[0034] The described implementations of the subject can include one or more features alone or in combination.

[0035] Furthermore, in some implementations, data can be collected at regular intervals (e.g., continuously), curated in a remote operations center, and loaded into a database with spatial and temporal indexing capabilities. For example, the data can be analyzed during collection for unloading start and end signals and then, in combination with location and time information and data records, determined which product transport container (e.g., grain truck or trailer) was positioned at a given location at that time, provided the equipment's dimensions and characteristics are known. In this example, after identifying a match, a "virtual load" record can be created or expanded for the device receiving the load, containing predefined load metrics and characteristics, such as weight, volume, loading time, product condition, and more.Data acquisition and processing can be automated, for example, based on load signals, location, and time alignment, without requiring operator intervention. Furthermore, if the destination transport container, such as a trolley, already contains one or more parts of another load at the time of pickup, the load quality information for all partially filled loads can be aggregated as appropriate.

[0036] The term "exemplary" is used here to serve as an example, a case, or an illustration. Any aspect or embodiment described herein as "exemplary" is not necessarily to be interpreted as being advantageous over other aspects or embodiments. Instead, the use of the word "exemplary" is intended to illustrate concepts in a concrete way. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is to say, unless otherwise specified or it is not clear from the context, "X uses A or B" is intended to mean any of the natural inclusive permutations. That is to say, if X uses A, uses XB, or uses both A and B, then "X uses A or B" is satisfied by any of the above cases. Furthermore, at least one of A and B and / or the like generally means A or B or both A and B.Furthermore, the articles “ein / eine / einer / eines”, as used in this application and in the attached claims, can generally be interpreted as meaning “one or more”, unless otherwise stated or it is clear from the context that they refer to a singular form.

[0037] Although the subject matter of the invention has been described in terms specific to structural features and / or methodological processes, it is understood that the subject matter of the invention defined in the appended claims is not necessarily limited to the specific features or processes described above. Rather, the specific features and actions described above are disclosed as exemplary realizations of the claims.

[0038] Although the disclosure has been shown and described with reference to one or more implementations, equivalent changes and modifications are apparent to the person skilled in the art based on reading and understanding the present description and the attached drawings. The disclosure includes all such modifications and changes and is limited only by the scope of protection of the following claims. In particular, with regard to the various functions performed by the components described above (e.g., elements, resources, etc.), the terms used to describe such components, unless otherwise specified, shall correspond to any component that performs the specified function of the described component (e.g., the element, resource, etc.).functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the function in the exemplary implementations of the disclosure presented herein. Although a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such a feature may, as desired and advantageous for a given or specific application, be combined with one or more other features of the other implementations. Furthermore, insofar as the expressions "includes," "has," "has," "with," or variants thereof are used either in the detailed description or in the claims, these expressions shall have an inclusive meaning similar to that of the expression "comprise."

[0039] The implementations have been described above. It is obvious to the person skilled in the art that the aforementioned methods and devices may be subject to changes and modifications without deviating from the general scope of protection of this disclosure. All such modifications and changes are hereby included insofar as they fall within the scope of protection of the accompanying claims or their equivalents.

Claims

[1] Hydraulic system for damping the high inertial forces generated by a body driven by a hydraulic motor, the hydraulic system comprising: a source of pressurized hydraulic fluid; a first supply line that is coupled to the source of the pressurized hydraulic fluid; a control valve connected to the first supply line; a working line that couples the control valve to the hydraulic motor; an outlet line coupled to the control valve, wherein the outlet line can be operated to return outlet fluid via a return reservoir to the source of the pressurized hydraulic fluid; a back pressure check valve located in the outlet line, wherein the back pressure check valve is set to a first pressure level; an anti-cavitation valve that is hydraulically positioned between the outlet line and the working line; an oil treatment circuit located in the outlet line between the backpressure check valve and the return tank; a second supply line extending between the first supply line and the outlet line; and a pressure reducing valve that is hydraulically arranged in the second supply line, wherein the pressure reducing valve is set to a second pressure level, wherein the second pressure head of the pressure reducing valve is greater than the first pressure head of the back pressure check valve, allowing hydraulic fluid to flow through the oil preparation circuit during periods of operation of the pressurized hydraulic fluid source. [2] Hydraulic system according to claim 1, further comprising: a flow control orifice located in the second supply line, wherein the flow control orifice can be operated to control a flow rate of hydraulic fluid flowing through the second supply line and through the oil preparation circuit. [3] Hydraulic system according to claim 1 or 2, wherein the oil preparation circuit comprises a fluid filter device located in the outlet line between the back pressure check valve and the return reservoir. [4] Hydraulic system according to one of the preceding claims, wherein the oil preparation circuit comprises a fluid cooler device located in the outlet line between the back pressure check valve and the return reservoir. [5] Hydraulic system according to claim 4, further comprising: a cooler bypass check valve that is hydraulically coupled in parallel to the fluid cooler device, wherein the cooler bypass check valve provides a path through which hydraulic oil can bypass the filter device. [6] Hydraulic system according to claim 5, wherein the cooler bypass check valve is set to a pressure greater than the second pressure head of the pressure reducing valve. [7] Hydraulic system according to one of the preceding claims, wherein the source of the pressurized hydraulic fluid comprises a pump. [8] Hydraulic system according to one of the preceding claims, wherein the control valve comprises a valve with a closed center. [9] Hydraulic system according to one of the preceding claims, further comprising a pressure relief valve mounted hydraulically parallel to the anti-cavitation valve. [10] Hydraulic system according to any of the preceding claims, wherein the hydraulic motor comprises one or more of the following: a hydraulic rotary motor; and / or a double-acting hydraulic cylinder. [11] Hydraulic system according to one of the preceding claims, wherein the source of the pressurized hydraulic fluid comprises a variable displacement pump.

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