Proportional valve spool with linear flow gain

An example spool includes a shaft varying in diameter along a length of the shaft, and a plurality of annular lands formed on the shaft and spaced-apart by respective reduced diameter annular neck portions. The plurality of annular lands comprise at least one annular metering land, and wherein the at least one annular metering land comprises: one or more sine notches formed as a portion of a sine wave, and one or more additional notches having a different shape from the one or more sine notches.

BACKGROUND

Hydraulic machinery commonly includes one or more valves. A valve can include a spool that is operated in response to the input command to control fluid flow and pressure to a hydraulic actuator of the machinery. The hydraulic actuator can have two chambers, and the valve controls fluid flow from a source of fluid to one chamber of the hydraulic actuator as well as fluid flow from the other chamber of the actuator to a fluid reservoir.

When the valve is actuated, the spool shifts or moves axially within a bore in a valve body of the valve. As the spool moves, a variable area orifice is formed between a metering edge of the spool and the inner surface of the valve body. The size of the area of such variable area orifice depends on the extent of axial motion of the spool and the shape of the metering edge of the spool.

The shape and size of the variable area orifice controls the flow gain of the spool, where the flow gain is the change of fluid flow rate for a given axial movement of the spool. In some applications, it may be desirable to have a substantially-linear flow gain such that movement of the hydraulic actuator controlled by the valve is predictable. It is with respect to these and other considerations that the disclosure made herein is presented.

SUMMARY

The present disclosure describes implementations that relate to a proportional valve spool with linear flow gain.

In a first example implementation, the present disclosure describes a spool configured to be movable in a longitudinal bore of a valve. The spool includes: a shaft varying in diameter along a length of the shaft; and a plurality of annular lands formed on the shaft and spaced-apart by respective reduced diameter annular neck portions, wherein the plurality of annular lands comprise at least one annular metering land, and wherein the at least one annular metering land comprises: one or more sine notches formed as a portion of a sine wave, and one or more additional notches having a different shape from the one or more sine notches.

In a second example implementation, the present disclosure describes a valve. The valve includes a valve body having (i) a longitudinal bore, (ii) a workport passage configured to be fluidly coupled to a hydraulic actuator, and (iii) a supply cavity configured to receive fluid from a source of fluid; and a spool axially movable in the longitudinal bore between a neutral position and a shifted position. The spool includes: a shaft varying in diameter along a length of the shaft, and a plurality of annular lands formed on the shaft and spaced-apart by respective reduced diameter annular neck portions, wherein the plurality of annular lands comprise at least one annular metering land. The at least one annular metering land comprises: one or more sine notches formed as a portion of a sine wave, and one or more additional notches having a different shape from the one or more sine notches. As the spool moves from the neutral position to the shifted position, the one or more sine notches and the one or more additional notches engage the workport passage to allow fluid flow from the supply cavity to the workport passage.

In a third example implementation, the present disclosure describes a hydraulic system including a source of fluid; a fluid reservoir; a hydraulic actuator having a first chamber and a second chamber therein; and a valve. The valve includes: a valve body having (i) a longitudinal bore, (ii) a first workport passage fluidly coupled to the first chamber of the hydraulic actuator, (iii) a second workport passage fluidly coupled to the second chamber of the hydraulic actuator, (iv) a supply cavity fluidly coupled to the source of fluid, and (v) a return cavity fluidly coupled to the fluid reservoir, and a spool axially movable in the longitudinal bore between a neutral position and a shifted position. The spool includes: (i) a shaft varying in diameter along a length of the shaft, (ii) a first annular metering land formed on the shaft, and (iii) a second annular metering land formed on the shaft, wherein the first annular metering land and the second annular metering land each has a plurality of notches comprising: one or more sine notches formed as a portion of a sine wave, and one or more additional notches having a different shape from the one or more sine notches, wherein as the spool moves from the neutral position to the shifted position, the plurality of notches of the first annular metering land engage the first workport passage to allow fluid flow from the supply cavity to the first workport passage, and the plurality of notches of the second annular metering land engage the second workport passage to allow fluid flow from the second workport passage to the return cavity.

In a fourth example implementation, the present disclosure describes a method for making a spool configured to be movable in a longitudinal bore of a valve. The method includes: (i) providing a shaft of the spool; (ii) forming a plurality of annular lands on the shaft such that the plurality of annular lands are spaced-apart by respective reduced diameter annular neck portions, wherein the plurality of annular lands comprise at least one annular metering land; (iii) forming one or more sine notches shaped as a portion of a sine wave; and (iv) forming one or more additional notches having a different shape from the one or more sine notches.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, implementations, and features described above, further aspects, implementations, and features will become apparent by reference to the figures and the following detailed description.

DETAILED DESCRIPTION

Hydraulic fluid flow in a hydraulic machine can be controlled using hydraulic control valves. A valve can include a valve body or housing having internal fluid passages, external ports, and a valve bore with a spool slidably-disposed within the valve bore. The valve is configured to control flow of fluid to and from a hydraulic actuator of the hydraulic machine.

The spool of the valve includes portions of differing diameter, such as a relatively smaller diameter portion (e.g., a neck portion) that acts as a flow area permitting flow of fluid across the spool, and a relatively larger diameter portion referred to as a land that restricts or blocks the flow of fluid across the spool, thereby controlling the flow of fluid through the valve. The spool can have a plurality of lands that interface with inner surfaces of the valve body to control fluid flow.

Particularly, the land can have an edge that can be referred to as a metering edge, and when the valve is actuated and the spool shifts within the spool bore a variable area orifice is formed between the metering edge and the inner surface of the valve body. The variable area orifice allows fluid flow therethrough. As the spool moves axially within the valve bore, the variable area of the orifice changes, thereby changing the fluid flow rate. The flow gain of the valve, i.e., the change in fluid flow rate through the valve for a given axial movement of the spool within the valve bore, is determined based on the change in the area of the orifice as the spool moves axially.

The spool can include one or more metering notches formed in the land, and such metering notches are configured to control fluid flow from a source of fluid into a downstream flow passage. The shape, depth, and number of the metering notches determine the flow gain of the spool.

In some applications, it may be desirable to have a substantially-linear flow gain such that movement of the hydraulic actuator controlled by the valve is predictable. Such substantially-linear flow characteristics may also provide for easier controller tuning. A nonlinear flow gain indicates that a given axial movement distance of the spool corresponds to a different amount of change in fluid flow rate based on where the spool is in its stroke. In other words, the flow rate through the valve versus the axial movement of the spool follows a nonlinear curve. In contrast, a linear flow gain indicates that the change in fluid flow rate versus the axial movement of the spool follows a substantially-straight line. Particularly, for a given axial distance of spool movement, the change in the fluid flow rate is consistent regardless of where the spool is in its stroke. Throughout this disclosure, the term “substantially-linear flow gain” indicates that the fluid flow rate of the valve versus the stroke of the spool follows a substantially-straight line, such that the flow rate can deviate from the line by no more than a threshold value (e.g., between 2% and 5% of maximum flow).

In one example, complex-shaped notches can be formed in the land to achieve a linear flow gain. Such complex notches can be formed in the spool via expensive machining techniques such as electrical discharge machining (EDM). Such manufacturing techniques can be costly. It may thus be desirable to have a spool that can achieve a substantially-linear flow gain using simpler notch shapes that are not complex to machine.

Disclosed herein are spools, valves, and systems that achieve substantially-linear flow gain. Particularly, an example spool has at least one annular metering land comprising one or more sine notches and one or more additional notches that have a different shape (e.g., generally square or triangular notches) from the at least one sine notch. The combination of the sine notch and the additional notch can achieve linear flow characteristics as described below.

FIG.1Aillustrates a partial, schematic representation of a hydraulic system100, in accordance with an example implementation.FIG.1Aparticularly illustrates a partial, perspective cross-sectional view of a valve102that is configured to control movement of a hydraulic actuator104by controlling fluid flow to and from the hydraulic actuator104.

The hydraulic system100includes a source106of fluid. The source106of fluid can be a pump (e.g., fixed displacement, variable displacement pump, a load-sense variable displacement pump, etc.), or an accumulator, as examples. A pump can receive fluid from a fluid tank or fluid reservoir108of the hydraulic system100, and the source106then pushes the fluid to the valve102.

The valve102has a valve body110that defines multiple fluid passages, cavities, and bores therein. Such fluid passages, cavities, and bores are fluidly coupled to various components of the hydraulic system100such as the source106, the fluid reservoir108, and the hydraulic actuator104.

In the example implementation ofFIG.1A, the hydraulic actuator104includes a cylinder112and a piston114slidably accommodated within the cylinder112. The term “slidably accommodated” is used throughout herein to indicate that a first component (e.g., the piston114) is positioned relative to a second component (e.g., the cylinder112) such that the first component is able to move relative to the second component.

The piston114includes a piston head116and a piston rod118extending from the piston head116along a central longitudinal axis direction of the cylinder112. The piston head116divides the inside or internal space of the cylinder112into a chamber120and a chamber122. The chamber120can be referred to as a cap chamber or head chamber, whereas the chamber122can be referred to as a rod chamber.

The valve102includes a workport124that is fluidly coupled (e.g., via a fluid lines such as a hose or tube) to the chamber120of the hydraulic actuator104, and the valve102also includes a workport126that is fluidly coupled to the chamber122of the hydraulic actuator104. Fluid lines are represented inFIG.1Awith dashed arrows. The valve102is configured to control supply fluid flow from the source106to the workports124,126, and control return fluid flow from the workports124,126to the fluid reservoir108.

The valve102has a spool128slidably accommodated (i.e., axially movable) in a longitudinal bore130formed in the valve body110. The spool128can be configured to be biased to a neutral or centered position by springs (not shown) disposed at the ends of the spool128.

FIG.1Billustrates a cross-sectional view of the valve102shown inFIG.1A, in accordance with an example implementation.FIG.1Bshows the spool128in a neutral position. When the spool128is in a neutral position, the spool128blocks fluid flow from the source106to the workports124,126. The term “block” is used throughout herein to indicate substantially preventing fluid flow except for minimal or leakage flow of drops per minute, for example.

The spool128can be actuated in either direction from the neutral position via various types of mechanisms. As an example for illustration, the spool128can be controlled by pilot valves such as pilot valves132,134shown as blocks inFIG.1A.

In an example, the pilot valves132,134are solenoid-operated. In one example, the pilot valves132,134can be configured as pressure reducing valves that receive pressurized fluid from the source106then generate a pilot fluid signal that is proportional to a magnitude of an electric command provided to a respective solenoid of the pilot valves132,134. In another example, the pilot valves132,134are hydro-mechanical valves that are manually controlled by joysticks or levers to provide the pilot fluid signal.

When actuated, the pilot valve132provides the pilot fluid signal to a pilot fluid passage136that communicates the pilot fluid signal to a first pilot cavity138at a first end of the spool128. The pilot fluid signal in the first pilot cavity138applies a fluid force on a pilot land139of the spool128to shift the spool128in a first direction (to the left inFIG.1A).

The pilot valve134can be configured similar to the pilot valve132and is configured to provide, when actuated, a pilot fluid signal to a pilot fluid passage140that communicates the pilot fluid signal to a second pilot cavity142at a second end of the spool128. The pilot fluid signal in the second pilot cavity142applies a fluid force on a pilot land143the spool128to shift the spool128in a second direction (to the right left inFIG.1A) opposite the first direction.

Supply fluid provided from the source106is provided through an inlet port of the valve102to a supply cavity144formed within the valve body110of the valve102. When the spool128moves axially in either direction, a variable metering orifice is formed as described below to allow fluid to flow from the supply cavity144to one of the workports124,126.

The spool128varies in diameter along its length to form annular metering lands separated by respective reduced diameter annular neck portions (also referred to as undercuts), thereby selectively interconnecting the various passages intercepting the longitudinal bore130to control flow of fluid to and from the workports124,126as the spool128shifts axially. The term “annular metering land” is used herein to indicate a generally cylindrical spool body portion having a larger diameter compared to the reduced diameter annular neck portions that separate the lands from each other. The annular metering lands of the spool128cooperate with internal surfaces of the valve body110to define variable metering orifices that allow fluid flow therethrough. For example, the spool128has annular metering land152, annular metering land154, annular metering land156, and annular metering land158configured to cooperate with the internal surfaces of the valve body110to form the variable metering orifices and control the fluid flow rate and direction through the valve102. The annular metering lands152-158each has a first diameter, and they are separated from each other by reduced diameter annular neck portions having a second diameter that is smaller than the first diameter. With this configuration, annular grooves are formed between each two adjacent annular metering lands of the annular metering lands150-158.

Each land of the annular metering lands152-158can block a respective fluid passage in the valve body110when the spool128is in the neutral position shown inFIG.1B. As the spool128shifts, a metering edge of a subset of the annular metering lands152-158moves past an edge of a respective internal surface bounding a fluid passage in the valve body110to form a variable metering orifice. The term “variable metering orifice” is used herein to indicate a spool-to-bore cylindrical area opening that forms between an annular metering land of the spool128and the internal surfaces of the valve body110when the spool128shifts axially therein. Thus, the variable metering orifice is a flow area that forms between the spool128and the internal surface of the valve body110, and the flow area varies in size based on the axial position of the spool128within the longitudinal bore130, e.g., the farther the spool128shifts axially, the larger the flow area.

The valve102has a return cavity146and a return cavity148that are fluidly coupled to each other via fluid passage150and are both fluidly coupled to the fluid reservoir108. The fluid reservoir108is drawn in two locations onFIG.1Ato reduce visual clutter but it should be understood that the return cavities146,148are fluidly coupled to an outlet port of the valve102, and the outlet port is fluidly coupled to the fluid reservoir108.

The valve102has a workport passage153that is fluidly coupled to the workport124. The valve102also has a workport passage155that is fluidly coupled to the workport126. When the spool128is in the neutral position shown inFIG.1B, fluid flow to the various cavities and passages can be blocked. Particularly, the annular metering land154blocks fluid flow from the supply cavity144to the workport passage153, the annular metering land156blocks fluid flow from the supply cavity144to the workport passage155, the annular metering land152blocks fluid flow from the workport passage153to the return cavity146, and the annular metering land158blocks fluid flow from the workport passage155to the return cavity148. As such, the piston114of the hydraulic actuator104might not move when the spool128is in the neutral position.

Referring toFIG.1A, actuating the pilot valve132or pilot valve134causes the spool128to move axially, thereby providing fluid flow to the hydraulic actuator104to move the piston114. For instance, if the pilot valve132is actuated and the spool128shifts axially to the left inFIG.1A, the annular metering land156can move to the extent that it moves past an edge of the internal surface of the valve body110interfacing therewith. As a result, a metering orifice is formed (as depicted inFIG.1A), allowing fluid flow from supply cavity144to the workport passage155.

The workport passage155is fluidly coupled to the workport126, and thus fluid flows through the workport passage155to the workport126, and then to the chamber122of the hydraulic actuator104to retract the piston114(e.g., move the piston114to the right inFIG.1A). Fluid discharged from the chamber120of the hydraulic actuator104flows through the workport124and the workport passage153, then through another metering orifice formed between the annular metering land152and the internal surface of the valve body110(as depicted inFIG.1A) to the return cavity146, which is fluidly coupled to the fluid reservoir108.

On the other hand, if the pilot valve134is actuated and the spool128shifts axially to the right inFIG.1A, the annular metering land154can move to the extent that it moves past an edge of the internal surface of the valve body110interfacing therewith. As a result, a metering orifice is formed, allowing fluid flow from the supply cavity144to the workport passage153. The workport passage153is fluidly coupled to the workport124, and thus fluid flows through the workport passage153to the workport124, and then to the chamber120of the hydraulic actuator104to extend the piston114(e.g., move the piston114to the left inFIG.1A). Fluid discharged from the chamber122of the hydraulic actuator104flows through the workport126and the workport passage155, then through another metering orifice formed between the annular metering land158and the internal surface of the valve body110to the return cavity148, which is fluidly coupled to the fluid reservoir108.

In some applications, it may be desirable to have a linear relationship between axial movement of the spool128and the amount of fluid flow rate provided to or from a workport of the workports124,126. Such linearity may render the performance of the valve102predictable. It may thus be desirable to configure the spool128to provide such linear relationship between its axial movement and the amount of fluid flow rate provided to and from the workports124,126. It may also be desirable to configure the spool128as such in a cost-effective way that does not involve expensive manufacturing techniques such as EDM.

FIG.2Aillustrates a perspective view of the spool128,FIG.2Billustrates a side elevational view of the spool128,FIG.2Cillustrates a cross-sectional view of the spool128taken along section line A-A shown inFIG.2B, in accordance with an example implementation. The spool128has a cylindrical spool body or shaft200that varies in diameter along its length to form the pilot lands139,143and the annular metering lands152-158separated by reduced diameter neck portions as described above. Particularly, the annular metering lands152,154form a first pair of opposed annular lands formed on the shaft200and spaced-apart by a first reduced diameter annular neck portion202. Similarly, the annular metering lands156,158form a second pair of opposed annular lands formed on the shaft200and spaced-apart by a second reduced diameter annular neck portion204.

Each of the annular metering lands152-158has a first plurality of notches formed as a portion of a sine wave and a second plurality of notches having a different shape disposed in a circular array about a circumference of the annular metering land. In an example, the first plurality of notches are interleaved with the second plurality of notches about a circumference of the respective annular land. As a particular example, each annular land can have a pair of sine notches and a pair of notches that have a different shape, e.g., having a generally square-shaped notch.

The term “plurality of notches” is used herein to indicate one or more notches. The term “sine notch” is used herein to refer to notch shaped as a portion of a geometric sine waveform formed along a portion of a meter edge of an annular metering land. Also, the term “interleaved” is used here to indicate that one of the sine notches is circumferentially-interposed between two notches having a different shape (i.e., are not shaped as sine notches), and similarly, each of the notches having the different shape is circumferentially-interposed between two sine notches.

For example, the annular metering land154has two sine notches and two additional notches having a different shape. Particularly, the annular metering land154has a first sine notch206formed in a proximal metering edge208of the annular metering land154and has a second sine notch210formed in the proximal metering edge208diametrically-opposite from the first sine notch206.

The annular metering land154further has a first square notch212circumferentially-interposed between the first sine notch206and the second sine notch210. The annular metering land154also has a second square notch214diametrically-opposite from the first square notch212and interposed circumferentially between the first sine notch206and the second sine notch210.

The annular metering land152is configured similar to the annular metering land154, with the respective sine notches being formed in the distal metering edge rather than a proximal metering edge. In other words, the notches of the annular metering land152face in an opposite direction compared to the notches of the annular metering land154. For example, the annular land152has a first sine notch216, a second sine notch217, a first square notch218, and a second square notch219(shown inFIG.2C). The other pair of annular metering lands, i.e., the annular metering lands156,158, is configured similar to the annular metering lands152,154.

Advantageously, sine notches can be formed in a cost-effective manner, e.g., via milling. Further, sine notches are characterized by having a large flow area gradient versus axial movement of the spool128. In other words, a small stroke or axial movement of the spool128exposes a large flow metering area due to the geometric shape of a sine notch. However, having the sine notches by themselves, i.e., the sine notches206,210without the square notches212,214, might not be sufficient to provide linear flow relationship.

FIG.3illustrates a graph300showing flow area characteristics of a spool with sine notches compared to substantially-linear flow area characteristics. The y-axis in the graph300represents flow area through a spool and the x-axis represents axial movement or stroke of the spool as a percentage of maximum stroke. Line302represents variation in flow area versus stroke of the spool. As an example, the line302may represents variation in flow area formed between sine notches similar to the sine notches206,210and the internal surfaces of the valve body110(assuming the annular metering land154only has the sine notches206,210without the square notches212,214) as the spool128moves axially in the distal direction. Line304represents substantially-linear variation in a flow area versus the stroke of a spool and is used to benchmark linearity of the spool associated with the line302. Notably, only a portion of a stroke (e.g., from 0% to 40% of maximum stroke) of the spool is plotted in the graph300.

As depicted, a spool with just sine notches as represented by the line302does not provide linear flow characteristics as represented by the line304. Vertical dashed arrows depicted in the graph300represent the additional flow area required to make up for the difference between the line304and the line302. Advantageously, while some conventional spools have many notches disposed about the entire circumference of a land of the spool to provide a particular flow area, a sine notch can provide the same flow area without occupying the entire circumference of the land. As such, there is enough room along a circumference of the land to form additional notches, such as the square notches212,214, and provide additional flow area that can make up for the flow area difference between the line304and the line302. Particularly, the geometry of the additional notches, e.g., the square notches212,214, can be adjusted in a “tuning” process to provide the appropriate amount of additional flow area such that the spool128provides a linear flow gain as the spool128moves axially within the valve body110.

FIG.4illustrates a graph400showing flow characteristics of different spools. The y-axis in the graph400represents flow rate as a percentage of maximum flow rate for a particular pump flow capacity and the x-axis represents commanded voltage to a solenoid that actuates the spool as a percentage of maximum command. A positive voltage indicates a voltage to a first solenoid that, when actuated, moves the spool in a given direction allowing flow from an actuator to the fluid reservoir through the valve (i.e., negative flow), whereas and a negative voltage indicates a voltage to a second solenoid that, when actuated, moves the spool in an opposite direction allowing flow from the source of fluid to the actuator through the valve (i.e., positive flow).

The graph400illustrates experimental results of flow gain characteristics for various spool configurations. Particularly, the graph400has four line plots corresponding to four different spool configurations. Line402represents a benchmark spool having substantially-linear flow characteristics. For example, the benchmark spool may be an expensive spool that can provide substantially-linear flow. Line404represents a spool that has sine notches only, without additional notches, and providing non-linear flow characteristics. For example, the line404can correspond to the spool associated with the line302ofFIG.3.

Lines406,408represent respective spools that having sine notches as well as additional notches to make up for the flow difference between the line402and the line404.FIG.5illustrates a partial view of a spool500associated with line406, andFIG.6illustrates a partial view of a spool600associated with line408, in accordance with example implementations. The spools500,600are variations of the spool128. Notably, in the graph400, flow rate tapers off near the end of stroke (i.e., at maximum command) due to the maximum available pump flow used in the experiments, and is not due to the geometry of the spools. Flow rates would be expected to continue with a greater pump flow.

Referring toFIGS.5-6, in addition to respective sine notches, the spool500has an annular metering land502(e.g., representing the annular metering land154) having a square notch504with a width Y, whereas the spool600has an annular metering land602(e.g., representing the annular metering land154) having a square notch604with a width X. As illustrated byFIGS.5-6, Y is greater than X.

As illustrated by the lines406,408inFIG.4, the spools500,600provide make up flow relative to the spool associated with the line404. However, the line406indicates that the width Y is larger than required and the make-up flow rate of the spool500is larger than the amount required to match the benchmark spool represented by the line402. The line408of the spool600with the smaller width X is closer to the line402of the benchmark spool. As such, the graph400illustrates that the width or other geometric characteristics of the square notch can be “tuned” to provide substantially-linear flow characteristics similar to the line402. For instance, a third width Z that is smaller than X might move the flow curve even closer to the line402of the benchmark spool.

The square notches212,218,219,504,604described above can be referred to as “generally” square notches as they may have radiuses at respective corners. For example, as shown inFIG.5, the square notch504has corners with radii506,508as opposed to sharp corners. Further, while the notches added to the sine spool to make up for the flow difference and achieve substantially-linear flow characteristics are shown and described as square notches, other geometries can be used to provide a linear flow gain.

FIG.7illustrates a perspective view of a spool700having sine notches and triangular notches, in accordance with an example implementation. The spool700is similar to the spool128in that it has four annular metering lands having sine notches. The spool700differs from the spool128in that the metering lands have additional notches that are generally triangular as opposed to being generally square.

For example, annular metering land702has a sine notch704(and a corresponding sine notch diametrically-opposite from the sine notch704) and has a triangular notch706. In an example, the annular metering land702has another triangular notch706diametrically-opposite from the triangular notch706.

Other shapes and configuration (e.g., geometries) of additional notches (other than the sine notches) can be used. For example, an additional notch can comprise a first portion have a first depth followed by, or contiguous to, a second portion have a second depth. Each portion may have a different geometric shape.

In another example, the additional notches (other than the sine notches) are not shaped similarly. For instance, the shape of the additional notches of the same annular metering land may differ (e.g., one notch is generally square, while another is generally triangular). In one example, the additional notches can be same on one metering land, but differ from additional notches of another metering land.

Further, although the four annular metering lands of the spools128,700are configured in the same manner, in other example implementations, not all metering lands are configured similarly. For example, at least one metering land may be configured to have sine notches and additional notches to achieve a linear flow gain, while other metering lands are not configured in that manner.

FIG.8is a flowchart of a method800for making a spool of a valve, in accordance with an example implementation. For example, the method800can be implemented to make the spool128or the spool700.

The method800may include one or more operations, or actions as illustrated by one or more of blocks802-808. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. It should be understood that for this and other processes and methods disclosed herein, flowcharts show functionality and operation of one possible implementation of present examples. Alternative implementations are included within the scope of the examples of the present disclosure in which functions may be executed out of order from that shown or discussed, including substantially concurrent or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art.

At block802, the method800includes providing a shaft (e.g., the shaft200) of the spool (e.g., the spool128,500,600,700).

At block804, the method800includes forming a plurality of annular lands on the shaft such that the plurality of annular lands are spaced-apart by respective reduced diameter annular neck portions, wherein the plurality of annular lands comprise at least one annular metering land (e.g., any of the annular metering lands152-158,502,602,702).

At block806, the method800includes forming one or more sine notches shaped as a portion of a sine wave (e.g., any of the sine notches206,210,216,217).

At block806, the method800includes forming one or more additional notches (e.g., the square notches212,214,218,219,504,604or the triangular notch706) having a different shape from the one or more sine notches.

The method800can further include any of the operations described throughout the disclosure.

The detailed description above describes various features and operations of the disclosed systems with reference to the accompanying figures. The illustrative implementations described herein are not meant to be limiting. Certain aspects of the disclosed systems can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

Further, devices or systems may be used or configured to perform functions presented in the figures. In some instances, components of the devices and/or systems may be configured to perform the functions such that the components are actually configured and structured (with hardware and/or software) to enable such performance. In other examples, components of the devices and/or systems may be arranged to be adapted to, capable of, or suited for performing the functions, such as when operated in a specific manner.

Embodiments of the present disclosure can thus relate to one of the enumerated example embodiment (EEEs) listed below.

EEE 1 is a spool configured to be movable in a longitudinal bore of a valve, the spool comprising: a shaft varying in diameter along a length of the shaft; and a plurality of annular lands formed on the shaft and spaced-apart by respective reduced diameter annular neck portions, wherein the plurality of annular lands comprise at least one annular metering land, and wherein the at least one annular metering land comprises: one or more sine notches formed as a portion of a sine wave, and one or more additional notches having a different shape from the one or more sine notches.

EEE 2 is the spool of EEE 1, wherein the at least one annular metering land comprise: a first pair of opposed annular metering lands formed on the shaft and spaced-apart by a first reduced diameter annular neck portion; and a second pair of opposed annular metering lands formed on the shaft and spaced-apart by a second reduced diameter annular neck portion.

EEE 3 is the spool of EEE 2, wherein each annular metering land of the first pair and second pair of opposed annular metering lands comprise respective one or more sine notches and respective one or more additional notches having the different shape from the one or more sine notches.

EEE 4 is the spool of any of EEEs 1-3, wherein the one or more sine notches comprise two sine notches, wherein the one or more additional notches comprise two additional notches, and wherein the two sine notches and the two additional notches are disposed in a circular array about a circumference of the at least one annular metering land.

EEE 5 is the spool of EEE 4, wherein the two sine notches are interleaved with the two additional notches, such that each sine notch is circumferentially-interposed between the two additional notches.

EEE 6 is the spool of any of EEEs 1-5, wherein the one or more additional notches are formed generally as a square-shaped notch.

EEE 7 is the spool of any of EEEs 1-5, wherein the one or more additional notches are formed generally as a triangular notch.

EEE 8 is a valve comprising: a valve body having (i) a longitudinal bore, (ii) a workport passage configured to be fluidly coupled to a hydraulic actuator, and (iii) a supply cavity configured to receive fluid from a source of fluid; and a spool axially movable in the longitudinal bore between a neutral position and a shifted position, wherein the spool comprises: a shaft varying in diameter along a length of the shaft, and a plurality of annular lands formed on the shaft and spaced-apart by respective reduced diameter annular neck portions, wherein the plurality of annular lands comprise at least one annular metering land, wherein the at least one annular metering land comprises: one or more sine notches formed as a portion of a sine wave, and one or more additional notches having a different shape from the one or more sine notches, wherein as the spool moves from the neutral position to the shifted position, the one or more sine notches and the one or more additional notches engage the workport passage to allow fluid flow from the supply cavity to the workport passage.

EEE 9 is the valve of EEE 8, wherein the at least one annular metering land comprise: a first pair of opposed annular metering lands formed on the shaft and spaced-apart by a first reduced diameter annular neck portion; and a second pair of opposed annular metering lands formed on the shaft and spaced-apart by a second reduced diameter annular neck portion.

EEE 10 is the valve of EEE 9, wherein each annular metering land of the first pair and second pair of opposed annular metering lands comprise respective one or more sine notches and respective one or more additional notches having the different shape from the one or more sine notches.

EEE 11 is the valve of any of EEEs 8-10, wherein the one or more sine notches comprise two sine notches, wherein the one or more additional notches comprise two additional notches, and wherein the two sine notches and the two additional notches are disposed in a circular array about a circumference of the at least one annular metering land.

EEE 12 is the valve of EEE 11, wherein the two sine notches are interleaved with the two additional notches, such that each sine notch is circumferentially-interposed between the two additional notches.

EEE 13 is the valve of any of EEEs 8-12, wherein the one or more additional notches are formed generally as a square-shaped notch or as a triangular notch.

EEE 14 is a hydraulic system comprising: a source of fluid; a fluid reservoir; a hydraulic actuator having a first chamber and a second chamber therein; and a valve comprising: a valve body having (i) a longitudinal bore, (ii) a first workport passage fluidly coupled to the first chamber of the hydraulic actuator, (iii) a second workport passage fluidly coupled to the second chamber of the hydraulic actuator, (iv) a supply cavity fluidly coupled to the source of fluid, and (v) a return cavity fluidly coupled to the fluid reservoir, and a spool axially movable in the longitudinal bore between a neutral position and a shifted position, wherein the spool comprises: (i) a shaft varying in diameter along a length of the shaft, (ii) a first annular metering land formed on the shaft, and (iii) a second annular metering land formed on the shaft, wherein the first annular metering land and the second annular metering land each has a plurality of notches comprising: one or more sine notches formed as a portion of a sine wave, and one or more additional notches having a different shape from the one or more sine notches, wherein as the spool moves from the neutral position to the shifted position, the plurality of notches of the first annular metering land engage the first workport passage to allow fluid flow from the supply cavity to the first workport passage, and the plurality of notches of the second annular metering land engage the second workport passage to allow fluid flow from the second workport passage to the return cavity.

EEE 15 is the hydraulic system of EEE 14, wherein the shifted position is a first shifted position associated with a first direction of movement of the spool, wherein the spool further comprises a third annular metering land formed on the shaft, and a fourth annular metering land formed on the shaft, wherein the third annular metering land and the fourth annular metering land each has a plurality of notches comprising: one or more sine notches, and one or more additional notches having a different shape from the one or more sine notches, wherein as the spool moves to a second shifted position in a second direction opposite the first direction, the plurality of notches of the third annular metering land engage the second workport passage to allow fluid flow from the supply cavity to the second workport passage, and the plurality of notches of the fourth annular metering land engage the first workport passage to allow fluid flow from the first workport passage to the return cavity.

EEE 16 is the hydraulic system of any of EEEs 14-15, wherein the one or more sine notches comprise two sine notches, wherein the one or more additional notches comprise two additional notches, and wherein the two sine notches and the two additional notches are disposed in a circular array about a circumference of the at least one annular metering land.

EEE 17 is the hydraulic system of EEE 16, wherein the two sine notches are interleaved with the two additional notches, such that each sine notch is circumferentially-interposed between the two additional notches.

EEE 18 is a method for making a spool configured to be movable in a longitudinal bore of a valve, the method comprising: providing a shaft of the spool; forming a plurality of annular lands on the shaft such that the plurality of annular lands are spaced-apart by respective reduced diameter annular neck portions, wherein the plurality of annular lands comprise at least one annular metering land; forming one or more sine notches shaped as a portion of a sine wave; and forming one or more additional notches having a different shape from the one or more sine notches.

EEE 19 is the method of EEE 18, wherein forming the one or more additional notches comprises: forming the one or more additional notches generally as a square-shaped notch or as a triangular notch.

EEE 20 is the method of any of EEEs 18-19, wherein forming the plurality of annular lands comprises: forming a first pair of opposed annular metering lands on the shaft such that the first pair of opposed annular metering lands are spaced-apart by a first reduced diameter annular neck portion; and forming a second pair of opposed annular metering lands such that the second pair of opposed annular metering lands are spaced-apart by a second reduced diameter annular neck portion.