DESC:DESCRIPTION
A PRIORITY AND CLOSED CENTER, LOAD SENSING OF HYDRAULIC STEERING SYSTEM CIRCUIT IN HEAVY TRUCKS
FIELD OF INVENTION
[001] The present subject matter described herein, relates to a hydraulic steering system. The present subject matter, in particularly, relates to a priority and load sensing based closed center steering control unit to enhance the steering effort in heavy dump truck.
BACKGROUND
[002] Background description includes information that may be useful in understanding the present subject matter. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed subject matter, or that any publication specifically or implicitly referenced is prior art.
[003] A conventional heavy dump truck hydraulic system involves steering, body hoist & brake oil cooling circuit. Steering operation is achieved with the help of dedicated pump, direction control valve (demand valve) to split oil flow to steering and body hoisting circuit, and open center type steering control unit.
[004] Uncomfortable steering or steering hard is a common technical problem reported often in case of Open center type steering control unit with built-in provision due to release of excess flow of oil to auxiliary system irrespective of demand to Steering operation. The main cause for uncomfortable steering related issue in open center type Steering control Unit is due to lack of dynamic signal between steering control unit & direction control valve which gives the pump flow to steering.
[005] Existing technology suggests switching over to the higher flow handling open center with power beyond type steering control unit for the existing steering hydraulic circuit.
[006] As an example of the prior art, US Patent. No: US8360531B2 discloses a priority flow control valve for supplying operating pressure has a first orientation in which operating pressure is provided at a controlled flow port and a second orientation in which operating pressure is provided at the controlled flow port and an excess flow port. A steering control unit has an inlet port for receiving operating pressure and an outlet port for communicating a steering control load sense signal. A brake control unit has an inlet port for receiving operating pressure and an outlet port for communicating a braking control load sense signal. The inlet port of the brake control unit and the inlet port of the steering control unit are connected to the controlled flow port.
[007] Existing prior art such as CN208978949Udiscloses a load sensing hydraulic steering gear. The check valve comprises a shell, a valve element and a valve sleeve, a metering device composed of a rotor and a stator is connected into the shell through a spring piece set, a shifting pin and a mechanical feedback device of a transmission shaft. An LS safety valve assembly for protecting the pressure of the steering hydraulic system is installed on the shell, a one-way throttle valve assembly is integrated on an oil way between the valve sleeve and the LS safety valve assembly of the shell, and the one-way throttle valve assembly is composed of a valve seat, a one-way steel ball, a gear rod pin, a one-way throttle valve inlet, a throttle hole and a one-way throttle valve outlet. By the adoption of the technical scheme, the load sensing type hydraulic steering gear is simple in structure, convenient to assemble and install and reasonable in design, pipeline shaking and accompanying steering noise of the designed load sensing type hydraulic steering gear in the working process.
[008] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
[009] Thus, there remains a need for a priority and load sensing based closed center steering control unit for effortless steering operation.
OBJECTS OF THE DISCLOSURE
[0010] In view of the foregoing limitations inherent in the state of the art, some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0011] The principal objective of the present subject matter is to develop a priority and load sensing based closed center steering control unit to enhance the steering effort in heavy dump truck.
[0012] It is another object of the present disclosure to propose a priority and load sensing based closed center steering control unit to prioritize steering operation.
[0013] It is yet another object of the present disclosure to propose a priority and load sensing based closed center steering control unit to direct the flow of oil to steering cylinders when steering operation is underway.
[0014] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY
[0015] One or more drawbacks of existing open center type steering control unit, and additional advantages are provided through the present priority and load sensing based closed center steering control unit as disclosed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0016] The present disclosure relates to a priority and closed center, load sensing of hydraulic steering system circuit comprises a hydraulic tank configured to contain oil. A pump to draw oil from the hydraulic tank. A high pressure filter to manage the contamination level in oil. A demand valve receives the filtered oil from the high pressure filter further through the check valve. A hoist system receives input from the demand valve and the priority valve. The demand valve supply oil to the priority valve and the priority valve to prioritize steering operation, wherein a steering control unit control steering operation using load sensing pilot signal. The steering control unit having cross over relief valve for operating a steering cylinder (LH) and a steering cylinder (RH).
[0017] The present disclosure relates to a method of controlling priority and closed center, load sensing of hydraulic steering system circuit, comprising the steps of: configuring a hydraulic tank to store oil. Drawing oil from the hydraulic tank using a pump. Determining the contamination level in oil using a high pressure filter. Receiving the filtered oil from the high pressure filter through the check valve to a demand valve. Receiving input from the demand valve and the priority valve to a hoist system. Supplying oil, the to the priority valve through the demand valve and prioritizing steering operation using the priority valve. Controlling the steering operation using a steering control unit using load sensing pilot signal and operating a steering cylinder (LH) and a steering cylinder (RH) using the steering control unit by a cross over relief valve.
[0018] In an aspect, steering is prioritized based on the dynamic signal or load sensing signal from steering control unit.
[0019] In an aspect, the priority valve ensures dynamic signal and flow to the steering or auxiliary function in the hydraulic circuit which in turn prioritize steering operation and at the same time load on hydraulic pump will be eliminated when steering and auxiliary operation is not in use.
[0020] In an aspect, close center, load sensing type steering control unit with higher displacement enhances the flow providing for steering cylinders thereby increasing the effortless steering in the equipment.
[0021] Other objects, features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF DRAWINGS
[0022] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0023] FIG. 1illustrates layout of hydraulic components in hydraulic circuit for steering system of heavy dump truck in accordance with an embodiment of the present disclosure;
[0024] FIG. 2 illustrates a hydraulic steering system circuit with closed center steering control unit in accordance with an exemplary embodiment of the present invention.
[0025] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
[0026] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0027] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0028] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0029] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0030] Embodiments explained herein pertain to a priority and closed center, load sensing of hydraulic steering system circuit 100. FIG. 1illustrates layout of hydraulic components in hydraulic steering system circuit 100 of heavy dump truck in accordance with an embodiment of the present disclosure. Oil delivered from the demand valve 110 enters the priority valve 112. The priority valve 112 comprises five ports such as a controlled flow port 130, an excess flow port 128, a T-port 124, a P-port 132 and a load sensing port 126 (as shown in FIG.1).
[0031] In a preferred embodiment the closed center steering control unit 114 with dynamic signal and load sensing signal involves two more components called a closed centered type steering control unit 114 and a priority valve 112.Further the priority valve 112 comprises a supply port and a return line port (not shown in FIG.1).When operator starts to turn the steering wheel, oil flows to the steering cylinders (118, 120) (as shown in FIG.2) through the close center steering control unit114 at the same time load sensing from the steering control unit 114 transfer pilot signal to the priority valve112 such that flow path is fully kept opened and in turn aids the steering action through steering cylinder operation. When operator stops steering, immediately the flow partially reduces, leaving the oil for excess flow port128.
[0032] In one embodiment the priority and load sensing based closed center steering control unit 114 enhance the steering effort in heavy dump truck. Instead of open center with power beyond type (with higher displacement feature), the hydraulic steering systemcircuit100adopts priority, load sensing and close center type steering control unit 114with higher displacement capability along with priority valve112 to enhance steering effort and to achieve power beyond option in steering hydraulic circuit.
[0033] In one embodiment the steering is prioritized based on the dynamic signal or load sensing signal from steering control unit 114. The priority valve 112 ensures dynamic signal and flow to the steering or auxiliary function in the hydraulic circuit which in turn prioritize steering operation and at the same time load on hydraulic pump is eliminated during which steering and auxiliary operation is not in use. The close center, load sensing type steering control unit 114 with higher displacement enhances the flow providing for steering cylinders (118,120) thereby increasing the effortless steering in the equipment.
[0034] Referring to FIG. 2 illustrates a hydraulic steering system circuit100 with closed center steering control unit114in accordance with an exemplary embodiment of the present invention. The hydraulic steering systemcircuit100 involves a hydraulic tank 102containing oil, a pump 104to draw oil from the hydraulic tank102, a high pressure filter 106to manage the contamination level in oil, a check valve108, a demand valve110, a priority valve 112to prioritize steering operation when operator starts to turn the steering wheel and a closed center steering control unit114 to control steering cylinders (i.e) a steering cylinder (LH) 118 and a steering cylinder (LH) 120.
[0035] In one embodiment in the pump supplies, oil from the hydraulic tank102 to the high pressure filter106 manages contamination in oil. The high pressure filter106 further supplies the filtered oil to the demand valve110 through the check valve108. The demand valve110 is a direction hoist control valve122, which delivers constant oil flow to the steering circuit irrespective of engine speed.
[0036] In one embodiment the dynamic signal between the closed center steering control unit114 and the priority valve112divert the pump flow to steering, based on the operator's demand and enhances steering comfortability.
[0037] In one embodiment a method of controlling priority and closed center, load sensing of hydraulic steering system circuit 100, comprising the following steps. Step 1: configuring a hydraulic tank102 to store oil. Step 2: Drawing oil from the hydraulic tank102 using a pump104. Step 3: Determining the contamination level in oil using a high pressure filter106. Step 4: Receiving the filtered oil from the high pressure filter 106 through the check valve108 to a demand valve 110. Step 5: Receiving input from the demand valve 110 and the priority valve 112 to a hoist system 116. Step 6: Supplying oil to the priority valve 112 through the demand valve 110 and prioritizing steering operation using the priority valve112. Step 7: Controlling the steering operation using a steering control unit 114 using load sensing pilot signal and operating a steering cylinder (LH) 118. Step 8: a steering cylinder (RH) 120 using the steering control unit 114 by a cross over relief valve.
[0038] In a preferred embodiment steering is prioritized based on the dynamic signal or load sensing signal from the closed center steering control unit114. Also, the priority valve112 ensures dynamic signal and flow to the steering or auxiliary function in the hydraulic circuit which in turn prioritize steering operation and simultaneously load on the hydraulic pump is eliminated when steering and auxiliary operation is not functional. Further, the close center load sensing type steering control unit114 with higher displacement enhances the flow provided for the steering cylinders (118, 120) thereby increasing effortless steering in the equipment.
[0039] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0040] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0041] Although the above detailed description illustrates closed center steering control unit for hydraulic steering system. It will be clear to one of skill in the art that the invention discloses about heavy dump trucks equipped with closed center steering control unit. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given above.
TECHNICAL ADVANTAGE
[0042] The present disclosure proposes a hydraulic steering system which is simple in construction and economical.
[0043] The present disclosure proposes a priority and load sensing based closed center steering control unit which operates as an effortless steering operation
[0044] The present disclosure proposes the hydraulic steering system with comfortable steering.
[0045] The present disclosure proposes the hydraulic steering system which is less costly to produce.
[0046] Furthermore, each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0047] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[0048] Furthermore, those skilled in the art can appreciate that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0049] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0050] While the foregoing describes various embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof. The scope of the present disclosure is determined by the claims that follow. The present disclosure is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
,CLAIMS:WE CLAIM:
1. A priority and closed center, load sensing of hydraulic steering system circuit (100), comprising:
a hydraulic tank (102) configured for oil storage;
a pump (104) to draw oil from the hydraulic tank (102);
a high pressure filter (106) to control the contamination level in oil;
a demand valve (110) receives the filtered oil from the high pressure filter (106) through the check valve (108);
a hoist system (116) receives input from the demand valve (110) and the priority valve (112);
the demand valve (110) supply oil to the priority valve (112) and the priority valve (112) prioritize steering operation, wherein a steering control unit (114) control steering operation using load sensing pilot signal, wherein
the steering control unit (114) having cross over relief valve for operating a steering cylinder (LH) (118) and a steering cylinder (RH) (120).
2. The priority and closed center, load sensing of hydraulic system circuit (100) of claim 1, wherein the priority valve (112) comprises a T-port (124), a load sensing port (126), an excess flow port (128), a controlled flow port (130), and a P-port (132).
3. The priority and closed center, load sensing of hydraulic steering system circuit (100) of claim 1, wherein the dynamic signal between the steering control unit (114) and the priority valve (112) diverts the pump flow to steering, based on the operator's demand.
4. The priority and closed center, load sensing of hydraulic steering system circuit (100) of claim 1, wherein the steering is prioritized based on the dynamic signal or load sensing signal from the steering control unit (114).
5. The priority and closed center, load sensing of hydraulic steering system circuit (100) of claim 1, wherein the load on the hydraulic pump is eliminated during which steering and auxiliary operation is not functional.
6. The priority and closed center, load sensing of hydraulic steering system circuit (100) of claim 1, wherein the steering control unit (114) with higher displacement enhances the flow for the steering cylinder (LH) (118) and the steering cylinder (RH) (120) thereby increasing effortless steering.
7. The priority and closed center, load sensing of hydraulic steering system circuit (100) of claim 1, wherein when operator stops steering, the oil flow partially reduces and the remaining oil pass through the excess flow port (128).
8. A method of controlling priority and closed center, load sensing of hydraulic steering system circuit (100), comprising the steps of:
configuring a hydraulic tank (102) to store oil;
drawing oil from the hydraulic tank (102) using a pump (104);
determining the contamination level in oil using a high pressure filter (106);
receiving the filtered oil from the high pressure filter (106) through the check valve (108) to a demand valve (110);
receiving input from the demand valve (110) and the priority valve (112) to a hoist system (116);
supplying oil to the priority valve (112) through the demand valve (110) and prioritizing steering operation using the priority valve (112);
controlling the steering operation using a steering control unit (114) using load sensing pilot signal; and
operating a steering cylinder (LH) (118) and a steering cylinder (RH) (120) using the steering control unit (114) by a cross over relief valve.