Electronically commutated hydraulic machine with reduced generation of resonance effects and method for operating the same

Abstract

A hydraulic apparatus comprising an electronic commutated machine having a plurality of working chambers controlled on each cycle of working chamber volume to perform either an effective cycle or an ineffective cycle of working chamber volume, only a limited fraction of cycles being allowed to be effective cycles to avoid generating a frequency of effective cycles which causes low frequency resonance. A demand signal can be quantised to a fraction m / n, where n is an integer below a threshold value selected to avoid a repeating pattern of effective cycles which exceeds a cut-off length.

Description

Technical Field

[0001] This invention relates to the field of electronically commutated hydraulic presses. Background Technology

[0002] Known electro-reversing hydraulic presses, in which the displacement of working fluid in each working chamber is controlled, for each individual working chamber volume cycle, by active control of at least a low-pressure valve and, in some embodiments (e.g., if the machine is used as a motor), a high-pressure valve, the active control being phased with the working chamber volume cycle, the low-pressure valve connecting each working chamber to a low-pressure manifold, and the high-pressure valve connecting each working chamber to a high-pressure manifold. Such a machine can respond quickly to changes in demand and can make the output very closely matched to fluctuating demand signals.

[0003] This invention particularly relates to an electronic commutator that distributes effective cycles with a working chamber volume containing a net working fluid discharge and ineffective cycles without a working chamber volume containing a net working fluid discharge. Typically, most or all of the effective cycles are full-stroke cycles, in which the working chamber discharges a predetermined maximum displacement of the working fluid by means of a timing appropriate to control valve actuation signals. It is also known to adjust the fraction of the maximum displacement generated during the effective cycle by operating so-called partial-stroke cycles, regulating a low-pressure valve and, optionally, a high-pressure valve. However, such machines typically distribute effective and ineffective cycles, with the effective cycles being full-stroke cycles, and the fraction of effective cycles (effective cycle fraction) varying to achieve the desired segmented displacement, rather than operating only with partial-stroke cycles.

[0004] We have found that problems can arise when such machines are operated at certain fractions of their maximum output. Examples of this can be found at both low and high fractions of their maximum output. At low fractions, the machine may only perform occasional effective cycles, interspersed with ineffective cycles, resulting in highly pulsating flow. We have found that this pulsating flow can sometimes lead to vibrations (especially low-frequency vibrations) and resonance effects. For example, if such a machine is operated at 5% of its maximum displacement per shaft rotation, and this is implemented by performing one effective cycle followed by 19 consecutive ineffective cycles, and then repeating the pattern, and if the working chambers are equidistant in phase, this will cause vibrations at 1 / 20th of the working chamber's selected frequency (the frequency at which the working chamber performs effective or ineffective cycles). If this corresponds to the resonant frequency of a component of the equipment, it can lead to unwanted shaking or damage. For example, if the equipment is an excavator, then low-frequency pulsating flow can cause shaking in the operator's cab. Therefore, the repetitive pattern of activation of the working chamber (e.g., the cylinder block) (i.e., the working chamber performing effective cycles) results in the generation of a corresponding motion frequency (and in some cases its harmonics).

[0005] Resonance can also occur due to the cylinder block operating in a mode of ineffective cycles. For example, if the same machine is running at 95% of its maximum displacement, it will primarily operate in effective cycles, with each 1 / 20th of a cycle being an ineffective cycle. This inactive cylinder block mode can again produce resonance at a frequency equal to 1 / 20th of the working chamber's actuation frequency. Strong resonance can also occur exactly above and below 50% of the maximum displacement.

[0006] Therefore, the present invention seeks to provide an electronically commutated hydraulic press that distributes effective and ineffective circulation within the working chamber volume, thereby suppressing or avoiding the generation of specific resonant frequencies, particularly low frequencies.

[0007] WO 2015 / 040360 (Abrahams et al.) discloses a machine in which the mode of a regulating valve actuation signal is such that the frequency of one or more intensity peaks of the spectrum of the effective and ineffective circulation modes of the working chamber is not maintained within one or more undesired frequency ranges. This invention seeks to provide an alternative method that is generally less complex to implement. Summary of the Invention

[0008] According to a first aspect of the invention, a method of operating an apparatus is provided, the apparatus comprising: a prime mover and a plurality of hydraulic actuators; a hydraulic press having a rotatable shaft driven and engaged with the prime mover, and comprising a plurality of working chambers having volumes that cyclically change with rotation of the rotatable shaft (e.g., each chamber is defined by a cylinder in which a piston reciprocates during use).

[0009] A hydraulic circuit that extends between a group of one or more working chambers of a hydraulic press and one or more hydraulic actuators.

[0010] Each working chamber of the hydraulic press includes a low-pressure valve for regulating the flow of hydraulic fluid between the working chamber and a low-pressure manifold, and a high-pressure valve for regulating the flow of hydraulic fluid between the working chamber and a high-pressure manifold.

[0011] The hydraulic mechanism is configured to actively control at least the low-pressure valves (and in some embodiments, also the high-pressure valves) of a group of one or more working chambers in response to a demand signal, to select the net hydraulic fluid discharge of each working chamber over a cycle in each working chamber volume, and thereby select the net hydraulic fluid discharge of a group of one or more working chambers.

[0012] The method includes controlling the valve to cause each working chamber to perform an effective or ineffective cycle of the working chamber volume during a cycle of each working chamber volume.

[0013] The feature is that the fraction of working chambers performing effective cycles is variable and selected from multiple discrete fractions.

[0014] According to a second aspect of the invention, an apparatus is provided comprising: a prime mover and a plurality of hydraulic actuators; a hydraulic press having a rotatable shaft driven to engage with the prime mover, and comprising a plurality of working chambers having volumes that cyclically change with rotation of the rotatable shaft (e.g., each chamber may be defined by a cylinder in which a piston reciprocates during use).

[0015] A hydraulic circuit that extends between a group of one or more working chambers of a hydraulic press and one or more hydraulic actuators.

[0016] Each working chamber of the hydraulic press includes a low-pressure valve for regulating the flow of hydraulic fluid between the working chamber and a low-pressure manifold, and a high-pressure valve for regulating the flow of hydraulic fluid between the working chamber and a high-pressure manifold.

[0017] The hydraulic press includes a controller configured to actively control at least low-pressure valves (and in some embodiments, high-pressure valves) of a group of one or more working chambers in response to a demand signal, to select the net hydraulic fluid discharge of each working chamber over a cycle in each working chamber volume, and thereby select the net hydraulic fluid discharge of the group of one or more working chambers.

[0018] The controller is configured (e.g., programmed) to control the valve so that each working chamber performs a valid or invalid cycle of the working chamber volume during each cycle of the working chamber volume.

[0019] The device is characterized in that the fraction of the working chambers performing the effective cycle is variable and selected from a plurality of discrete fractions.

[0020] It is possible that the controller of the hydraulic press is configured such that the fraction of the working chambers performing an effective cycle is variable, and can be one of multiple discrete fractions. Alternatively, the device may be configured such that the controller of the hydraulic press receives only the demand signal selected from multiple discrete values, thereby making the fraction of the working chambers performing an effective cycle variable and selected from multiple discrete fractions.

[0021] The “active cycles” we refer to are cycles that generate a net displacement of the working chamber volume of the working fluid. The “inactive cycles” we refer to are cycles that do not generate a net displacement of the working chamber volume of the working fluid (typically one or both of the low-pressure and high-pressure valves remain closed throughout the cycle). Typically, active and inactive cycles are distributed to meet the demand indicated by the demand signal. This contrasts with machines that only perform active cycles, where the displacement of the active cycles can vary. The “working chamber selection decision” we refer to is the decision of whether a working chamber undergoes an active or inactive cycle of the working chamber volume. These typically occur at each of several discrete angles of the rotatable shaft. The “active cycle fraction” we refer to is the fraction of working chambers that perform active cycles. This is also known as the activation fraction. The demand signal is typically processed as a “displacement fraction” Fd, which is the target fraction of the maximum displacement of the working fluid per rotation of the rotatable shaft. Considering the current rotational speed of the rotatable shaft and the number of working chambers grouped together connected to the same high-pressure manifold and actuator(s), the demand expressed in volume (volume of working fluid per second) can be converted to a displacement fraction. The demand signal relates to the demand for a combined fluid displacement of a group of one or more working chambers fluidly connected to the one or more hydraulic actuators via a hydraulic circuit. Other groups of one or more working chambers may exist, fluidly connected to one or more other hydraulic actuators having corresponding demand signals.

[0022] Multiple discrete fractions are selected to avoid resonant oscillations at unwanted frequencies, particularly below a predetermined minimum frequency. Typically, multiple discrete fractions are selected to avoid generating any repetitive patterns of both valid and invalid cycles with a length greater than the predetermined maximum repeating pattern length of the working chamber volume. Generally, when multiple discrete fractions are represented as irreducible fractions, they do not include any fractions with denominators greater than the predetermined maximum denominator.

[0023] This can avoid or reduce the negative effects of resonant oscillations, which could otherwise result in damage to components, unacceptable noise and vibration experienced by the operator. Equipment containing hydraulic pumps and motors may be damaged by oscillations caused by the operation of the hydraulic pump or motor.

[0024] The selection of multiple discrete fractions usually takes into account the predetermined operating speed of the rotatable shaft (which can be the typical or minimum typical operating speed) (because the rotational speed of the rotatable shaft determines the frequency of the working chamber circulation).

[0025] Typically, the demand signal responded to by a hydraulic press is quantized, having one of a plurality of discrete values. These discrete values ​​can also be discrete fractions (e.g., the number of effective cycles). These discrete values ​​may be the same as discrete fractions. However, this will depend on the unit of the demand signal and how the demand signal is processed to determine whether the working chamber performs an effective or ineffective cycle. Therefore, since at least low-pressure valves (and in some embodiments, high-pressure valves) control the working chambers to select the net displacement of hydraulic fluid in each working chamber for each cycle of the working chamber volume, the number of working chambers performing effective cycles is variable and is selected from a plurality of discrete fractions.

[0026] Multiple discrete fractions (and, where applicable, multiple discrete values) can be viewed as a set (a finite number) of discrete fractions (values), from which one value is selected at any given time. Multiple discrete fractions (or values) are typically stored on a solid-state storage device that communicates electronically with the machine's controller and is read from the solid-state memory as needed.

[0027] It is possible to receive and quantize (optionally continuously) the demand signal, for example, by selecting the discrete value closest to the received demand, or the next discrete value above or below the received demand signal. A hysteresis can be applied in the quantization step to avoid jitter.

[0028] Multiple discrete values ​​and multiple discrete fractions can represent the corresponding fraction (displacement fraction, Fd) of the maximum displacement of the working fluid per rotation of a rotatable shaft consisting of one or more working chambers.

[0029] There may be steps to determine discrete values, such as calculating them or reading them from memory, and they may be variable, for example, depending on the rotational speed of the rotatable shaft.

[0030] When the demand signal is quantized, the effective and ineffective cycle modes at these discrete displacement fractions (“quantized displacement”) result in cylinder activation modes with known frequency content (i.e., cylinder modes that perform effective or ineffective cycles), and therefore, the minimum frequency repetition of the effective cylinder mode is known.

[0031] Therefore, unwanted vibrations are reduced by controlling the mode of the valve command signal to prevent certain ranges of Fd. This does mean that the target net displacement cannot always be accurately met. However, in some closed-loop feedback systems, any errors resulting from this can be corrected because the machine sometimes operates at a discrete fraction exceeding the required displacement fraction and sometimes at a discrete fraction below the required displacement fraction.

[0032] An example of a system that cannot tolerate volumetric errors is a system based on open-loop displacement control, which requires the pump to deliver the precise volume of fluid required. Closed-loop pressure control with an integral term, such as an LS (load-sensing) system, is also affected by quantization. Displacement demand can cycle between two discrete levels when the continuous displacement demand level lies between them in a quantization table. For example, suppose we are in a steady state and we control to 20 bar. A lower displacement level would provide 18 bar, and a higher displacement level would provide 25 bar. Let's assume the most recent discrete level is lower than the continuous displacement level. The selected discrete level delivers a lower flow rate from the pump than the flow rate required by the continuous displacement level. It delivers 18 bar. This causes the integrator term in the pressure control loop to rise. At some point, this integrator term will become large enough to bring the continuous displacement demand level close to the higher discrete displacement level, and the selected discrete displacement will rise to that higher level. The delivered pressure will be 25 bar, so the integrator term will begin to decrease. At some point, it will become low enough to reduce the displacement level required by the pump. This cycle may continue indefinitely, and it may occur at low frequencies, introducing low-frequency content into the hydraulic lines.

[0033] However, the opening or closing time of at least the low-pressure valve (and in some embodiments, the high-pressure valve) can be adjusted to change the fraction of the maximum stroke volume discharged from each working chamber during each effective cycle. The fraction of the maximum stroke discharged can be coordinated with the effective cycle fraction (e.g., via a device controller) to cause the hydraulic press to discharge a displacement fraction indicated by a demand signal, while constraining the effective cycle fraction to only one of a plurality of discrete fractions.

[0034] Although the fraction of the working chamber performing an effective cycle is restricted to one of several discrete fractions, this may make it possible to produce a continuous range of displacement per revolution of the rotatable shaft. This would effectively create a (fully) variable displacement hydraulic press with all displacements per revolution of the rotatable shaft (from zero to full) (fully continuous displacement can be achieved using a finite number of discrete effective cycle fractions). All fractions of the maximum displacement can be achieved by allowing a range of variation from 0-100% of the maximum stroke volume, but the maximum stroke volume variation can also be constrained to 0-5% and 95-100% or 0-10% and 90-100%. It is possible to make the fraction of the maximum stroke volume discharged by each working chamber during each cycle vary between 0 and x% and y% to 100%, where x < 25 and y > 75, or even where x <= 10 and y >= 90. This is because when the fluid flow rate entering or leaving the working chamber is limited, only a portion of the stroke displacement within these ranges can be generated by the actuation valve near the start or end of the stroke (within the circulation of the working chamber volume).

[0035] The discrete fractions and / or discrete values ​​of the demand signal may or may not be equally spaced. The discrete fractions and / or discrete values ​​of the demand signal may or may not vary with the rotational speed of the rotatable shaft. If they vary with the rotational speed of the rotatable shaft, they can be selected to reduce the generation of low-frequency components. For example, there may be fewer than 1000 or fewer than 100 discrete values. When the demand signal is digital, we are not referring to the possible values ​​imposed by binary logic, but rather to a subset of values ​​that can be digitally represented considering the bit size of the demand signal. Therefore, considering the bit length, discrete values ​​typically represent digital values ​​that less than 10%, less than 1%, or less than 0.1% of the demand signal might have.

[0036] Possibly, the controller receives a demand signal (typically a continuous demand signal) and determines a corresponding series of values ​​that correspond to the patterns of effective and / or ineffective cycles of the working chamber volume, thereby satisfying the demand signal (i.e., when the demand signal (F) generated by the patterns of effective and / or ineffective cycles of the working chamber volume... d When averaged over a time period). The method may include receiving a demand signal (typically a continuous demand signal) and determining a corresponding series of values ​​corresponding to the patterns of effective and / or ineffective cycles of the working chamber volume, thereby satisfying the demand signal (i.e., when the demand signal (F) generated by the patterns of effective and / or ineffective cycles of the working chamber volume is satisfied). d (When averaged over a period of time).

[0037] For example, the controller can receive a continuous demand signal of 90% of the maximum displacement and can determine a series of values, including at least 100 values, or preferably at least 500 values, or more preferably at least 1000 values. The series of values ​​may include a repeating sequence, and therefore the patterns of effective and / or ineffective cycles may include periods corresponding to the repeating sequence. The average effective cycles over a period of time will satisfy a requirement as close as possible to 90% without generating low-frequency content in the sequence.

[0038] In some embodiments, the net discharge of the working fluid is the same during each effective cycle. This discharge is typically the maximum discharge of the working fluid in each working chamber.

[0039] The term "fraction" refers to a number ranging from 0 to 1, expressed as a ratio with an integer numerator and an integer denominator. The term "irreducible fraction" refers to a fraction whose numerator and denominator do not share any integer factors. For example, 3 / 6 is the same as the irreducible fraction 1 / 2.

[0040] Typically, when discrete fractions are represented as irreducible fractions, the range of denominators is up to the maximum value, chosen to avoid repetitive patterns of working chamber actuation with frequencies lower than a predetermined minimum. Typically, when discrete fractions are represented as irreducible fractions, they contain fractions where each integer denominator is a multiple of the integer i, up to the maximum denominator. It is possible that when discrete fractions are represented as irreducible fractions, they contain fractions where each integer denominator is a multiple of the integer i, up to the maximum denominator. (For example, for i = 3, the denominators would be 3, 6, 9, 12… Many such fractions would have smaller integers when represented as irreducible fractions, but the fractions would typically include 1 / i, 1 / 2i, 1 / 3i…(3i-1) / 3i, (2i-1) / 2i, i-1 / i).

[0041] Multiple fractions can include each irreducible fraction or consist of it (usually along with 0 and 1), and irreducible fractions have denominators from 1 to n and corresponding numerators m from 1 to n-1 (where m and n are integers).

[0042] Multiple integers can include or consist of each irreducible fraction (usually along with 0 and 1), where an irreducible fraction has a denominator that is a multiple of an integer i from i to n and a numerator m from 1 to n-1, where i > 1. In the case that each working chamber has the same redundancy, i can be equal to the redundancy. By "redundancy," we mean the number of working chambers in the same set operating at the same phase (and thus giving the fluid displacement equivalent to the axis angle).

[0043] According to the aforementioned method, the smallest non-zero fraction among the plurality of discrete fractions is usually 1 / n, and the second smallest fraction among the plurality of discrete fractions is 1 / (n-1), where n is an integer.

[0044] It is possible to select the smallest non-zero fraction among multiple fractions such that, at the target operating rotational speed of the rotatable shaft, the frequency of the repetition pattern of the effective cycle of the working chamber volume is higher than a predetermined minimum permissible frequency.

[0045] It is possible that, considering the case that two or more working chambers have the same phase or that there is a non-uniform phase difference between two or more working chambers, the smallest non-zero portion of a plurality of discrete fractions is selected. This may include processing data representing the relative phase of the working chambers and / or taking into account that some working chambers may have synchronized working chamber volume cycles. The method may include calculating the number of consecutive working chambers required to generate a repeating pattern in a group of working chambers, typically taking into account the phase difference and / or redundancy of the group of working chambers.

[0046] However, it is possible to determine the discrete fraction (effective cycle fraction) and / or multiple discrete values ​​(where applicable) of the quantization demand signal through simulation or experimentation. In this case, in response to the simulation or experiment, the discrete fraction and / or discrete values ​​of the quantization demand signal are included in multiple discrete fractions (or values) that show the frequency content of the resulting high-pressure manifold pressure or valve activation current or other signal meets one or more acceptable spectral criteria, and / or where the frequency content below the cutoff frequency is below a threshold, or where the effect of selecting effective and ineffective cycles is found to be acceptable (e.g., in response to operator feedback or measurement or calculation of the movement of one or more parts of the equipment), or if they do not meet these criteria, they are excluded. Thus, multiple discrete fractions and / or discrete values ​​can be established through trial and error. The minimum frequency can be determined experimentally or through simulation (whether during design, manufacturing, or operation) and used to calculate the maximum denominator n.

[0047] The discrete fraction (effective cycle fraction) and / or multiple discrete values ​​(where applicable) of the quantization demand signal do not need to be determined before machine manufacturing or commissioning or even before operation, but can be calculated during operation and / or in real time taking into account predetermined parameters (e.g., working chamber phase and redundancy data, minimum frequency) and / or currently measured parameters (e.g., shaft rotation speed).

[0048] It is possible that multiple discrete fractions and / or multiple discrete values ​​(where applicable, the demand signal is quantized into multiple discrete values) vary in response to the rotational speed of the rotatable shaft or another operating parameter of the device. That is, the multiple discrete fractions (or values) can be a set of discrete fractions (or values), and different sets of discrete fractions (or values) can be used at different rotational speeds of the rotatable shaft or at different values ​​or ranges of another operating parameter of the device. The method may include switching from using a first set of discrete fractions (or values) to a second set of discrete fractions (or values) when the rotational speed of the rotatable shaft exceeds a threshold.

[0049] It is possible that the multiple discrete fractions (or values) used can vary in response to changes in the number and phase of the working chambers in the group of working chambers connected to the high-pressure manifold.

[0050] It is possible to determine whether the working chamber undergoes an effective or ineffective cycle of the working chamber volume by comparing the time history of the displacement demand (e.g., the received displacement demand signal) with the time history of the actual displacement, for example by increasing the accumulator based on the displacement demand signal and decreasing the accumulator based on the amount of working fluid discharged.

[0051] The method is extended in a third aspect to a method for calculating multiple discrete fractions for use in the method of the first aspect or the device of the second aspect, the method comprising: inputting a minimum permissible frequency, a target operating speed of the rotatable shaft, and data indicating the number and / or phase difference between the working chambers of the machine, and / or the phase difference between a group of working chambers ( wherein the group is defined as the working chambers of the group sharing a common hydraulic output); calculating an integer n (typically a maximum integer) of the working chamber determination point between effective cycles, which would result in a cylinder activation frequency that exceeds only the minimum permissible frequency, and including 1 / n in the multiple discrete fractions.

[0052] The method also includes, after removing duplicate values, multiple discrete fractions comprising a denominator of at most n integers and a numerator of at most n-1 integers.

[0053] The method may include forming the plurality of discrete fractions from a plurality of fractions having denominators that are all integer multiples (greater than 1).

[0054] The method may include forming a plurality of discrete fractions, including fractions 1 / i, 1 / 2i, and typically also 1 / 3i, where i is an integer. i may be equal to the redundancy of the working chamber.

[0055] Typically, duplicate values ​​are removed. Fractions can be re-represented as irreducible fractions. Fractions can be converted to binary numbers.

[0056] This method may include removing one or more discrete fractions from a plurality of discrete fractions to avoid generating repetitive cylinder activation patterns with frequency components below a certain value. This could be due to frequency components caused by unequal cylinder phases.

[0057] The method may also include a step of verifying whether the candidate discrete fractions (e.g., effective cycle fractions) are associated with a obtained discrete level of output fluid displacement, which has sufficient resolution to satisfy one or more operational smoothness criteria. If the candidate fractions do not result in sufficiently smooth operation (due to the intervals between the discrete fractions), the method may include generating an error or failure method, recalculating the discrete fractions, or respecificating the hydraulic press (e.g., deciding to use a hydraulic press with more working chambers). Where applicable, the discrete fractions may be used as the value of a quantized demand signal and / or multiple discrete fractions.

[0058] The method may include the step of storing multiple discrete fractions on a solid-state storage device for retrieval during operation.

[0059] The effective and ineffective cycles of the working chamber volume executed by the working chamber include finite time period patterns with a given number of effective cycles. For example, the patterns of effective and ineffective cycles may have a minimum time period of at least 0.001s, or at least 0.005s, or at least 0.01s, and / or may have a maximum time period of at most 0.1s, or at most 0.5s.

[0060] In the example machine, the minimum time period can be 2.4 ms (caused by the activation frequency of all 12 equally spaced cylinders at a maximum speed of 2500 RPM). Those skilled in the art will understand that, in the case of higher speeds of the prime mover or more cylinders, the minimum time period can be 1 ms (or less).

[0061] In the main embodiment, all frequencies below 5Hz are preferably removed, thus corresponding to a time period of 0.2s.

[0062] Typically, the acceptable time period is selected based on the acceptable frequency content. For applications requiring the removal of all frequencies below a certain value, it is necessary to specify a maximum acceptable time period. Starting from this maximum acceptable time period, the acceptable range of effective cycle fractions is selected based on the number of cylinders and the operating range of the prime mover. For example, the acceptable range of effective cycle fractions can be selected to include multiple discrete effective cycle fractions generated using integer numerator and denominator values. The denominators of multiple effective cycle fractions can be selected based on the rotational speed of the rotatable shaft; for example, the denominators can be chosen such that the time period is higher than the minimum time period. Having a short time period is beneficial because it corresponds to more frequent effective or ineffective cycles in the working chamber volume, and thus removes low frequency content from patterns of effective and ineffective cycles. Typically, the acceptable value of the denominator for a finite number of fractions varies according to the rotational speed of the rotatable shaft. However, it is possible that the available effective cycle fractions do not change with the prime mover speed and are selected to remove low frequency content at the minimum prime mover speed. Therefore, frequency content at higher speeds is also acceptable.

[0063] For a given number of valid cycles, the frequency of the working chamber executing valid or invalid cycles is proportional to the rotational speed (revolutions per second) of the rotatable shaft. For a given number of valid cycles, the sequence of valid and invalid cycles within the working chamber volume does not depend on the shaft speed. However, the time between the components of the sequence does vary with the shaft speed. Therefore, the frequency generated by a particular sequence of valid and invalid cycles is proportional to the rotational speed of the rotatable shaft.

[0064] What matters is the repetition pattern of the effective or ineffective chambers, not whether a specific cylinder is enabled or disabled. For example, the sequence 0,0,0,1,0,0,0,1 has the same fundamental frequency as the sequence 1,1,1,0,1,1,1,0.

[0065] Therefore, the present invention recognizes that a hydraulic press will produce vibrations with a peak intensity, the frequency of which depends on the pattern of effective and ineffective cycles performed by the working chamber, and that for a given sequence of effective and ineffective cycles, the peak intensity is proportional to the rotational speed of the rotatable shaft.

[0066] The method may include selecting a minimum permissible frequency (e.g., 5 Hz, 10 Hz) and then creating a quantization list of multiple discrete valid cycle fractions (e.g., the value of Fd and / or, where applicable, the value of the demand signal quantized), the fractions being selected as one or more patterns that result in valid and invalid cycles, wherein said patterns have only frequency content above the minimum permissible frequency. The controller may be configured to determine the minimum permissible frequency (e.g., 5 Hz, 10 Hz) and then create a quantization list of multiple discrete fractions (e.g., the value of Fd and / or, where applicable, the value of the demand signal quantized), the values ​​being selected as one or more patterns that result in valid and invalid cycles, wherein said patterns have only frequency content above the minimum permissible frequency.

[0067] Discrete values ​​(in the quantization list) typically correspond to discrete fractions (of the working chambers performing effective cycles), but this is not necessary because the demand signal does not need to be represented by displacement fractions.

[0068] The discrete fractions (and / or discrete values) can depend on the number of cylinders in the machine and / or the rotational operating speed of the machine's rotatable shafts (because the rotational speed of the rotatable shafts and the number of cylinders will affect the frequency of a given demand value). For each valid cycle fraction, the minimum frequency that exists can be calculated. As the machine runs, the (filtered) demand signal is transmitted to the hydraulic press's controller. However, the calculation of the continuous demand signal and the quantization of the demand signal and / or the selection of the discrete valid cycle fractions can both be performed internally within the controller itself.

[0069] The minimum permissible frequency may be below 20 Hz, or even below 10 Hz. This invention is particularly useful for avoiding these types of low frequencies.

[0070] The invention extends in a fourth aspect to a solid-state storage device that stores a plurality of discrete fractions calculated by the method according to a third aspect of the invention. The method of the first aspect may include reading the discrete fractions from the solid-state storage device of the fourth aspect. The device of the second aspect may include the solid-state storage device of the fourth aspect in electronic communication with a controller.

[0071] The device can be a vehicle, typically an industrial vehicle. For example, it could be an excavator, telescopic forklift, or backhoe loader. It could also be a car, bus, truck, forklift, and / or wheel loader. It could be an injection molding machine or a waterjet cutting unit. The device can be a hydraulic power unit. It may include a hydraulic transmission. It could be a hydraulic hybrid vehicle transmission. It could be a renewable generator (e.g., a wind turbine generator or a wave or tidal generator). It may include a radio transceiver. It may include a battery. It may include electrical terminals for charging. It could be a rail vehicle. It could be a (non-industrial) passenger vehicle. However, it is possible that the device is not a vehicle.

[0072] A hydraulic press may include more than six or more than eight working chambers. It is possible that a hydraulic press includes more than twelve working chambers.

[0073] It is possible that the device is configured to calculate a demand signal in response to a measurement characteristic of a hydraulic circuit or one or more actuators. Typically, the device includes a controller configured to calculate the demand signal in response to a measurement characteristic of a hydraulic circuit or one or more actuators.

[0074] The invention also extends to a method of operating the device, which includes calculating a demand signal in response to measurement characteristics of a hydraulic circuit or one or more actuators.

[0075] Typically, the method includes detecting flow and / or pressure demand of at least one of one or more hydraulic actuators, or receiving a demand signal indicating the required pressure or flow based on the pressure and / or flow demand of one or more hydraulic actuators, and controlling the outflow or inflow of hydraulic fluid from each of a group of one or more working chambers fluidly connected to the one or more hydraulic actuators in response to the one or more hydraulic actuators.

[0076] The method may include adjusting the displacement of a group of one or more working chambers in response to a measured pressure. Therefore, the device typically has a negative flow control loop. Optionally, the device may include a feedforward controller configured to calculate a demand signal in response to a feedforward of a measured characteristic of the hydraulic circuit or one or more actuators (e.g., in addition to or as an alternative to a feedback controller configured to calculate the demand signal in response to feedback of a measured characteristic of the hydraulic circuit or one or more actuators).

[0077] For example, a demand signal can be determined in response to pressure and / or flow measurements. This demand signal may include pressure measurements taken at a throttle valve. The demand signal may indicate the fraction of the maximum displacement of hydraulic fluid to be discharged per revolution of a rotatable shaft by a group of one or more working chambers. This is referred to herein as Fd (fraction of maximum displacement per revolution). If each working chamber discharges the maximum possible volume of working fluid, then Fd equals the effective circulation fraction.

[0078] Prime movers are typically engaged with hydraulic presses. A prime mover has a rotatable shaft, which is typically coupled to a rotatable shaft of an ECM (and to which the prime mover can apply torque). The prime mover (e.g., an engine) and the hydraulic press may share a common shaft.

[0079] In the case of an excavator, multiple hydraulic actuators typically include (e.g., at least) two actuators for moving the tracks (e.g., for the movement of a vehicle, typically for the movement of an excavator), a rotary actuator (e.g., a motor) (e.g., for rotating the excavator cab relative to the excavator's base, which typically includes tracks), at least one ram actuator (e.g., for controlling the excavator boom, for example, for the boom and / or joystick), and at least two additional actuators (e.g., for controlling the movement of tools such as buckets).

[0080] One or more low-pressure manifolds may extend to the working chamber of the hydraulic press. One or more high-pressure manifolds may extend to the working chamber of the hydraulic press. The hydraulic circuit typically includes the high-pressure manifolds extending between the group of the one or more working chambers and the one or more actuators. The low-pressure manifolds may be part of one or more of the hydraulic circuits. Low-pressure manifold 54 and high-pressure manifold 58 refer to the relative pressure in the manifolds.

[0081] Possibly, at least the low-pressure valve (optionally a high-pressure valve, or both low-pressure and high-pressure valves) is an electronically controlled valve, and the device includes a controller that controls (e.g., electronically) the valve in a phase-dependent manner with respect to the circulation of the working chamber volume, thereby determining the net hydraulic fluid discharge of each working chamber in each circulation of the working chamber volume. The method may include controlling (e.g., electronically) the valve in a phase-dependent manner with respect to the circulation of the working chamber volume, thereby determining the net hydraulic fluid discharge of each working chamber in each circulation of the working chamber volume.

[0082] The flow rate and / or pressure requirements of one or more hydraulic actuator groups can be determined, for example, by measuring the flow rate of hydraulic fluid flowing to or from one or more hydraulic actuator groups, or by measuring the pressure of hydraulic fluid in or at the output or inlet of one or more hydraulic actuators. The flow rate and / or pressure requirements can be determined by one or more measured flow rates and / or measured pressures that are lower than expected values. A decrease in flow rate and / or measured pressure from expected values ​​indicates that insufficient flow to or from one or more hydraulic actuator groups is occurring. For example, it can be determined that the flow rate of hydraulic fluid flowing to the actuator is lower than expected (e.g., a target value), and the flow rate of hydraulic fluid flowing to the actuator can increase in response. It can be determined that the flow rate of hydraulic fluid from the actuator is higher than expected (e.g., a target value) (e.g., as the arm or other weight decreases), and the flow rate from the actuator can decrease in response. It is possible that an increase or decrease in pressure is detected at one or more hydraulic actuators, and a group of one or more working chambers connected to one or more hydraulic actuators is controlled to change (e.g., increase or decrease) the flow rate of hydraulic fluid from the group of one or more working chambers to one or more hydraulic actuators, or vice versa.

[0083] A group of one or more working chambers can be dynamically assigned to a corresponding group of one or more hydraulic actuators, thereby changing which one or more working chambers are connected to (e.g., a group of) hydraulic actuators, for example, by opening or closing electronically controlled valves (e.g., high-pressure and low-pressure valves described below) under the control of a controller. A group of (e.g., one or more) working chambers can be dynamically assigned to (corresponding) (e.g., one or more) actuator groups, thereby changing which working chambers of the machine are connected to which hydraulic actuators, for example, by opening and / or closing (e.g., electronically controlled) valves under the control of a controller. The net displacement of hydraulic fluid through each working chamber (and / or each hydraulic actuator) can be adjusted by regulating the net displacement of one or more working chambers connected to one or more hydraulic actuators. A group of one or more working chambers is typically connected to a corresponding group of one or more of the hydraulic actuators via the manifold.

[0084] The device typically includes a controller. The controller includes one or more processors that communicate electronically with the memory, and program code stored in the memory. The controller may be distributed and may include two or more controller modules (e.g., two or more processors). For example, the controller may include a hydraulic press controller (including one or more processors that communicate electronically with the memory, and program code stored in the memory) that controls a hydraulic press, and an equipment controller (including one or more processors that communicate electronically with the memory, and program code stored in the memory) that controls other components of the equipment (e.g., controlling valves to change the flow path of hydraulic fluid).

[0085] It is possible that the flow rate of hydraulic fluid received or output by each working chamber is independently controllable. Alternatively, the flow rate of hydraulic fluid received or generated by each working chamber can be independently controlled by selecting the net displacement of hydraulic fluid in each cycle of the working chamber volume. This selection is typically performed by the controller.

[0086] Flow and / or pressure requirements can be sensed by measuring the pressure of the hydraulic fluid at the input of the hydraulic actuator. In the case of a hydraulic press, flow requirements can be sensed by measuring, for example, the rotational speed of a rotating shaft, the translational speed of a stamping section, or the angular velocity of a joint. The measured flow and pressure can be summed, or the maximum value of the measured pressure or flow can be found.

[0087] The pressure and / or flow demand indication signal based on the hydraulic actuator can be a signal indicating the flow rate of hydraulic fluid, or the pressure of hydraulic fluid, or the torque on the shaft of the machine or the torque on the shaft of the hydraulic actuator driven by the machine, or the power output of the machine, or any other signal indicating the demand related to the pressure or flow requirements of one or more hydraulic actuators.

[0088] Typically, a hydraulic press can operate as a pump in pump mode or as a motor in motor mode. It is possible that some working chambers of the hydraulic press can be pumps (therefore some working chambers can output hydraulic fluid), while other working chambers can be motors (therefore some working chambers can input hydraulic fluid).

[0089] It is possible that the discrete values ​​vary with the rotational speed of the rotatable shaft and are selected to avoid generating undesirable and / or unacceptable frequencies when the hydraulic press controls the net displacement of a group of one or more working chambers, in order to meet quantization requirements.

[0090] Each working chamber is selectable in each cycle of its working chamber volume, for example, by a valve control module, to discharge a predetermined fixed volume of hydraulic fluid (effective cycle) or to undergo an ineffective cycle (also known as an idling cycle), where there is no net discharge of hydraulic fluid, thereby enabling the machine's net fluid throughput to dynamically match the demand indicated by the demand signal. The controller and / or valve control module is operable to cause each working chamber to undergo an effective or ineffective cycle by executing an algorithm (e.g., for each cycle of the working chamber volume). This method may include executing an algorithm to determine whether each working chamber undergoes an effective or ineffective cycle (e.g., for each cycle of the working chamber volume). This algorithm typically processes (e.g., quantified) demand signals. Attached Figure Description

[0091] Exemplary embodiments of the present invention will now be described with reference to the following accompanying drawings, in which:

[0092] Figure 1 This is a schematic diagram of a device according to the present invention, which includes an electro-reversing hydraulic press and an actuator;

[0093] Figure 2 This is a schematic diagram of an electronically commutated hydraulic press;

[0094] Figure 3 This explains the explanation by Figure 2 The process executed by the electronically commutated hydraulic press is to sequentially determine the net displacement of each cylinder.

[0095] Figure 4 This is a schematic diagram illustrating data processing to achieve quantification;

[0096] Figure 5 It is a graph showing the change of the quantized output in response to the received demand signal over time;

[0097] Figure 6 This is a flowchart of the process for creating a quantization table (multiple discrete scores); and

[0098] Figures 7A to 7C The effective cylinder block fraction as a function of displacement demand Fd is shown (7A), the partial stroke dimension as the maximum fraction as a function of displacement demand Fd (7B), and the scaling factor as a function of displacement demand Fd (7C). Detailed Implementation

[0099] Reference Figure 1For example, equipment 1 for a hydraulic excavator or other vehicle includes an electronically swerving hydraulic press 10 (hereinafter referred to as "ECM"). This ECM includes a first group 10A and a second group 10B of working chambers, each group being fluidly connected to a valve block 8 via a first fluid connection 21A and a second fluid connection 21B, respectively, such that the group of working chambers can be individually connected to one or more of high-pressure manifolds 22A, 22B, or 22C. Therefore, as described... Figure 1 As shown in the embodiment, ECM 10 includes two groups, 10A and 10B, each group including one or more working chambers, but the number of working chambers is not shown in the figure. ECM 10 functions as the hydraulic press described below, which will be referred to below. Figure 2 Further description. The ECM can be a pump or a motor, and in this example, it can operate as either a pump or a motor. The ECM is driven by a prime mover 2 via a rotating shaft 4. A low-pressure manifold 6 extends from the storage tank to the low-pressure side input of the ECM. On the high-pressure side, the ECM has a valve block 8 that can be actuated to selectively connect different groups 10A, 10B of one or more working chambers of the electronic commutator to high-pressure manifolds 22a, 22b, and 22c, thereby changing which working chambers are connected to each high-pressure manifold. All working chambers connected to the high-pressure manifolds (whether group 10A or group 10B, or both groups simultaneously, or one or more other groups) together function as a group of one or more working chambers connected via a hydraulic circuit to one or more hydraulic actuators, and it refers to the net discharge of working fluid from one or more working chambers in a particular group of one or more actuators that are controlled together to control or respond to a demand signal. This invention is also applicable to situations where the allocation of the working chambers to the actuators cannot be changed. Each of these high-pressure manifolds extends to an actuator, such as another hydraulic press 11. The press 11 can be of fixed or variable displacement, with valves that are electrically or mechanically (hydraulic) actuated and controlled, driving a load 12, such as one or more wheels of a vehicle, or another hydraulic actuator 16, 18, such as an excavator bucket or plunger, via another shaft 14. The actuators may function solely as reservoirs or solely as sources of hydraulic fluid, but depending on the actuation direction, some or all of the actuators may function as either reservoirs or sources. When the actuator is driven, the working chamber of the ECM connected to the actuator undergoes a pumping cycle; when driven by the actuator, the working chamber of the ECM connected to the actuator undergoes a motorized cycle.

[0100] The device includes a device controller 100 that receives control signals from the operator via one or more manual control units and receives feedback signals, such as actuator position signals or pressure signals from the individual hydraulic actuators 11, 16, 18 and / or high-pressure manifolds 22A, 22B, 22C and / or fluid connections 21A, 21B. The device controller 100 processes these signals and controls the device by calculating continuous variable demand signals for each group of working chambers and sending these signals to the ECM. Furthermore, in the example shown, the device controller can also periodically send control signals to the valve block 8 to reconfigure, for example, which working chambers are connected to which actuators in response to changes in current or future possible loads, thereby changing which working chambers are in which group of one or more working chambers. However, valves in the valve block can also be actuated via pilot pressure using hydraulic levers.

[0101] Figure 2 yes Figure 1 The diagram shows a portion of an ECM embodiment and illustrates a single group of working chambers currently connected to one or more actuators via a high-pressure manifold 54. Figure 2 Details are provided regarding the first group 10A, which comprises multiple working chambers (eight shown) having a cylinder 24 and a piston 28. The cylinder has a working volume 26 defined by its inner surface. The piston is driven by an eccentric cam 32 from a rotatable shaft 30 and reciprocates within the cylinder to cyclically change its working volume. The rotatable shaft is rigidly connected to and rotates with the drive shaft. A shaft position and speed sensor 34 determines the instantaneous angular position and rotational speed of the shaft and notifies the ECM controller 50 via signal line 36, enabling the ECM controller to determine the instantaneous phase of the cycle for each cylinder.

[0102] Each working chamber is associated with a low-pressure valve (LPV), which is in the form of an electronically actuated face-sealed lift valve 52. This lift valve has an associated working chamber and is operable to selectively seal a passage extending from the working chamber to a low-pressure hydraulic fluid manifold 54, which connects one or more working chambers, or indeed all of them as shown herein, to the low-pressure hydraulic fluid manifold of the ECM. The LPV is a normally open, solenoid-actuated valve that passively opens to provide fluid communication between the working chamber and the low-pressure hydraulic fluid manifold when the pressure in the working chamber is less than or equal to the pressure in the low-pressure hydraulic fluid manifold, i.e., during the intake stroke. However, it can be selectively closed via the low-pressure valve control line 56 under the active control of the ECM controller to disengage the working chamber from the low-pressure hydraulic fluid manifold. Alternatively, this valve can be a normally closed valve.

[0103] Each working chamber is also associated with a corresponding high-pressure valve (HPV) 64, which is in the form of a pressure-actuated delivery valve. Each HPV opens outward from its respective working chamber and is operable to seal a corresponding passage extending from the working chamber through valve block 8 to high-pressure hydraulic fluid manifolds 22, 58, which may connect one or more working chambers, or in fact... Figure 2 All working chambers are shown. The HPV is used as a normally closed pressure-opening check valve, which passively opens when the pressure in the working chamber exceeds the pressure in the high-pressure hydraulic fluid manifold. The HPV also functions as a normally closed electromagnetically actuated check valve, which, once opened by pressure in the associated working chamber, can be selectively kept open by the ECM controller via HPV control line 62. Normally, the HPV cannot be opened by the ECM controller against pressure in the high-pressure hydraulic fluid manifold. When pressure is present in the high-pressure hydraulic fluid manifold but not in the working chamber, the HPV may additionally open, or partially open, under the control of the ECM controller.

[0104] In pumping mode, the ECM controller selects the net displacement rate of hydraulic fluid from the working chamber to the high-pressure hydraulic fluid manifold by actively closing one or more low-pressure valves, typically near the maximum volume point in the circulation of the associated working chamber, thereby closing the path to the low-pressure hydraulic fluid manifold and discharging hydraulic fluid through the associated high-pressure valve on the subsequent compression stroke (but without actively keeping the high-pressure valve open). The ECM controller selects the number and sequence of LPV closures and HPV openings to generate flow, or shaft torque or power, to satisfy the selected net displacement rate.

[0105] In the maneuvering operation mode, the ECM controller selects the net discharge rate of hydraulic fluid from the ECM via the high-pressure hydraulic fluid manifold and actively closes one or more LPVs shortly before the minimum volume point in the circulation of the associated working chamber, closing the path to the low-pressure hydraulic fluid manifold. This causes the hydraulic fluid in the working chamber to be compressed for the remainder of the contraction stroke. When the pressure across the associated HPV is balanced, the associated HPV opens, and a small amount of hydraulic fluid is drawn out through it, which is kept open by the ECM controller. The ECM controller then actively keeps the associated HPV open, typically until near the maximum volume in the circulation of the associated working chamber, receiving hydraulic fluid from the high-pressure hydraulic fluid manifold into the working chamber and applying torque to the rotatable shaft.

[0106] And to determine whether to close the LPV on a cycle-by-cycle basis or keep the LPV open, the ECM controller is operable to change the precise phase of HPV closure relative to the changing working chamber volume, and thereby select the net discharge rate of hydraulic fluid from the high-pressure hydraulic fluid manifold to the low-pressure hydraulic fluid manifold and vice versa.

[0107] The arrows on the low-pressure fluid connection 6 and the high-pressure fluid connection 21A indicate the hydraulic fluid flow in motorized mode; in pumping mode, the flow is reversed. The pressure relief valve 66 protects the assembly within the ECM from damage.

[0108] During normal operation, the ECM distributes effective and ineffective cycles of the working chamber volume to meet the demands indicated by the received demand signals.

[0109] Figure 3 The process executed by ECM controller 50 is illustrated to sequentially determine the net displacement of each cylinder; a sequential start 200 is followed by setting multiple stored variable algorithm accumulators to zero at 202. Variable algorithm accumulators are maintained for each independently controlled group (as a group of one or more working chambers) for one or more cylinders, allowing each group to respond to independent demand signals. While "algorithm accumulator" is more commonly referred to as "accumulator" in computer science, the different terminology is used here to distinguish the entirely different concept of a hydraulic accumulator. The variable algorithm accumulator stores the difference between the hydraulic fluid displacement represented by the displacement demand and the actual displacement.

[0110] Then the ECM's rotatable shaft rotates until it reaches the determining point of a single cylinder block (204). For Figure 1 The example shown has eight cylinders, spaced equally in phase without any redundancy, so each decision point will be rotated 45 degrees apart by the rotatable shaft. The actual time interval between each decision point will therefore be the time interval required for the rotatable shaft to rotate 45 degrees, which is inversely proportional to the rotational speed of the rotatable shaft. However, in some embodiments, there will be different phases between the activation decision points in the working chambers, and there can be multiple working chambers that can be controlled independently but always have the same phase.

[0111] At each decision point, the ECM controller reads a demand signal in the form of a 206-fractional-displacement-value (Fd) for each group of working chambers of the ECM. This displacement fraction Fd is received from another controller (e.g., the equipment controller) or calculated internally using signals from the hydraulic circuit. For each group of working chambers, the ECM controller then calculates a 208-variable algorithmic sum, which equals the relevant algorithmic accumulator plus the demand displacement for that group. This sum takes into account the time period since the previous decision point, which can be variable, taking into account variations in the rotational speed of the rotatable shaft and possible phase changes between the working chamber decision points.

[0112] Next, the database 220 of working chamber states is referenced to check the state of the cylinders being considered in 210. For each cylinder 24, if damage is found or if it is not part of a different cylinder group connected to one or more actuators, no further action is taken on that cylinder. Once each cylinder (if any) that must be further considered at a decision point has been considered, the method is repeated from step 204 once the next decision point is reached.

[0113] For each cylinder associated with the decision point, the algorithmic sum of the relevant groups of working chambers is compared with a threshold.212 When the only option considered is an invalid cycle with no net displacement or a full-displacement valid cycle in which the maximum displacement of the hydraulic fluid in the selected cylinder is achieved, this value can simply be the maximum volume of hydraulic fluid that the cylinder can displace. However, the threshold may be higher or lower. For example, it may be less than the maximum displacement of a single cylinder, such as in the case where partial cycles are expected to be performed, where only a portion of the maximum displacement of the cylinder is displaced.

[0114] If the algorithmic sum is greater than or equal to the threshold, then cylinder block 24 is determined to undergo a valid cycle 214. Alternatively, if the algorithmic sum is not greater than or equal to the threshold, then cylinder block 24 is determined to be invalid 216 in the next cycle of its working volume and will have a net displacement of zero. The accumulator value is calculated based on the displacement subtracted from the algorithmic sum 218.

[0115] Control signals are then sent to the low-pressure valve 52 and high-pressure valve 64 of the cylinder 24 under consideration to cause the cylinder to undergo a defined effective or ineffective cycle. (In the case of pumping, the high-pressure valve may not be electronically controlled, and the control signal only relates to the low-pressure valve). For the specific valve associated with the cylinder under consideration, the control signal is transmitted across the corresponding (low-pressure) control line 56 and (high-pressure) control line 62.

[0116] For each group of working chambers (cylinder blocks), this step effectively considers the displacement demand represented by the displacement demand signal, and the difference between the previous displacement represented by the displacement demand signal and the previous net displacement determined by the ECM controller (in this case, in the form of a stored error). The time-averaged net displacement of the cylinder's hydraulic fluid is then matched with the time-averaged displacement represented by the displacement demand signal. If the algorithmic sum equals or exceeds a threshold, the cylinder undergoes a valid cycle in which it produces a net displacement of hydraulic fluid. In this case, the error value is set as the sum minus the effective cylinder displacement. Alternatively, if the algorithmic sum does not equal or exceed the threshold, the cylinder is invalid, and the algorithmic sum is not modified.

[0117] When one or more cylinders reach the next decision point, the process restarts from step 204.

[0118] Therefore, it can be seen that for each group of working chambers, the algorithm accumulator maintains a record of the difference between the required displacement and the actual displacement. In each cycle, the required displacement is added to the displacement error value and subtracted from the actually selected displacement. The algorithm accumulator effectively records the difference between the required displacement and the provided displacement, and a valid cycle occurs whenever the accumulated difference exceeds a threshold. Because a separate algorithm accumulator is maintained for each different group of cylinders connected to the same high-pressure manifold, the pressure in each high-pressure manifold connected to the corresponding actuator or the flow rate through each high-pressure manifold can be controlled independently.

[0119] Those skilled in the art will understand that the effect of this displacement determination algorithm can be achieved in several ways. For example, instead of subtracting the selected displacement from the algorithm accumulator variable, the required displacement and the delivered displacement can be added over a period of time, and the displacement of a single cylinder can be selected to maintain a uniform match between the two.

[0120] It can be seen that when the demand signal is low, the algorithm will result in highly pulsating pressure fluctuations due to the periodic distribution of effective cycles between ineffective cycles. If the demand signal is a fraction of 1 / n of the maximum demand and remains constant at that fraction, then every nth cycle of the working chamber volume will be an effective cycle, with the remainder being ineffective cycles, and there will be pulsating flow with a frequency equal to the frequency of the working chamber activation decision point 204 divided by n. For example, a similar effect will occur when the demand signal is close to but less than 100% of the maximum demand, as occasional ineffective cycles will occur periodically between other consecutive effective cycles.

[0121] Although these vibrations typically begin with relatively low amplitude, the amplitude can increase over time, especially if the frequency of the vibration is at (or close to) the resonant frequency of the vehicle (or part of the vehicle). If the amplitude increases beyond a predetermined maximum, these vibrations can cause damage.

[0122] According to the present invention, the demand signal passed to the ECM controller and used as the input to the above algorithm is quantized such that it has only one of a predetermined set of discrete values, as we will explain. These discrete values ​​are chosen to avoid generating repetitive patterns of cylinder activation exceeding a predetermined length, and therefore the frequency component is below the cutoff frequency.

[0123] Figure 4 This is a schematic diagram of data processing implemented by the equipment controller 100 and the ECM controller 50, which together realize the present invention. It will be apparent to those skilled in the art that the functions of the equipment controller and the ECM controller can be combined or further distributed. The equipment control program module 300 (represented by computer code executed by the equipment controller) processes feedback signals 310, 312, 314 received by the equipment controller from the actuators and high-pressure manifold. These signals may include pressure measurements, actuator position or speed measurements, etc. The equipment controller also receives operator command signals 316, which can be input via a user interface such as a touchscreen or keyboard, or via a manual control unit such as a lever or joystick for controlling actuators (e.g., for controlling the operation of hydraulic actuators of an excavator and / or driving the vehicle). This data is used to calculate the current displacement demand signals 301A, 301B, 301C for each group of working chambers. In this example, the displacement demand signal is represented as Fd (the fraction of the maximum displacement per rotation of the rotatable shaft). These signals are then digitally processed by the device controller to implement hysteresis using hysteresis logic 302A, 302B, 302C, which outputs partially processed displacement demand signals 303A, 303B, 303C.

[0124] Hysteresis is useful for preventing chatter between adjacent quantization steps and is used in all quantization methods. In systems without an integral term, such as in a negative flow control system, the degree of hysteresis is specific to the system's compliance and the pressure-displacement relationship (in some cases, the pressure-displacement relationship may be a proportional gain). Hysteresis is ineffective for systems with an integral term when using the effective cycle fraction of quantization and only the full pump stroke is available; it is only used to modify the displacement cycle frequency. When designing a hysteresis system, it is preferable to consider that the manual operator will effectively compensate for small errors between the generated and required displacement of hydraulic fluid, for example, by adjusting the actuator position through the joystick position. In some embodiments, hysteresis is provided only when the displacement demand decreases, rather than when the displacement demand increases. This is particularly useful in the variable stroke volume embodiment described below. Therefore, the feed to the ECM controller 50 and the reference Figure 3 The algorithm described processes continuous demand signals that are quantized and are often further processed to introduce hysteresis.

[0125] Then, the displacement requirements for some processing are quantified as 304A, 304B, and 304C. (Reference) Figure 5 Instead of transmitting the initially calculated displacement demand signal 400 to the ECM controller 50, the demand signal is quantized, even though it corresponds to one of several different displacement fractions 402A, 402B, 402C, 402D, 402E, etc. This is performed with reference to a solid-state memory storing a data structure 306 that sets multiple discrete fractions. Valid cycle fractions can also be calculated during operation without the need for a storage table. The quantized demand signals 305A, 305B, and 305C are then transmitted to the ECM controller 50. Valid cycle fractions can also be calculated during operation without the need for a storage table.

[0126] Discrete fractions are chosen to avoid generating effective or ineffective cycle modes of the cylinder block volume with frequency content below a defined cutoff frequency, assuming a predetermined minimum rotational speed of the rotatable shaft. Pressure pulsations in the hydraulic lines will occur in the enabled mode, consisting of effective and ineffective cycles of the cylinder block working volume, and will have the same frequency content. This vibration can be transmitted to components. The purpose of the quantification control method is to prevent the mechanical components of the system / vehicle (directly or indirectly, e.g., via operator excitation) from being excited at their natural frequency. This can happen if the cylinder is enabled at the same frequency as the natural frequency of the mechanical components, where there are some form of path (e.g., a mechanically coupled path) for transmitting vibration from the pump (or connected hoses / pipes) to the mechanical components.

[0127] Removing frequencies from the cylinder block activation mode using quantization techniques will prevent the ECM controller from commanding certain displacement levels. Displacement levels can be defined by the volume of fluid per shaft rotation or a fraction of the maximum fluid displacement per shaft rotation. When the continuous displacement level demand is not equal to one of the discrete displacement levels, the nearest discrete displacement level is selected, resulting in an error between the continuous displacement demand and the discrete displacement levels. Therefore, in this case, there will be an error between the pump's required volume and the delivered volume. This will not be a problem in the system where there is an error between the accurate volume of fluid produced and the volume delivered.

[0128] Furthermore, the operator can effectively compensate for minor errors between the required oil volume and the produced volume. The operator will adjust the joystick position to achieve the desired actuator position.

[0129] The importance of the "minimum frequency" lies in the fact that, when using quantization, frequencies below this level will not appear in the cylinder's activation mode. If the selected "minimum frequency" is higher than the component's natural frequency, then the mechanical component will not resonate at its natural frequency.

[0130] Therefore, the set of discrete fractions can consist of fractions with a denominator of at most an integer n, where n is chosen so that the effective cycle frequency of the cylinder volume is higher than the cutoff frequency at the expected speed of shaft rotation and at a displacement fraction of 1 / n.

[0131] For example, if a machine has 12 equally spaced cylinders rotating at 1000 rpm, then a cylinder selection decision will be made every (60 / 1000) / 12 = 5 milliseconds. If the largest denominator is 5, the cylinder will execute one effective cycle every 25 milliseconds, and the effective cycle fraction is 1 / 5, therefore the minimum frequency that occurs is 40 Hz (Hertz). This can be seen in the following example of cylinder activation modes:

[0132]

[0133] Table 1

[0134] The table above shows that when Fd = 1 / n (5 in this example), a pattern is generated that repeats once every n cylinders. For m / n, where m and n are integers and are represented as irreducible fractions (i.e., m and n have no common divisor other than 1), a pattern of sequence length n will reappear (during which m cylinders have undergone a valid cycle).

[0135] For example, an allowed group of fractions could be each fraction m / n, which is an irreducible fraction, where n is a predetermined maximum integer from 1 (5 in this example), and m is less than n (for every value of n). An example table for n=5 is shown below:

[0136] Allowed Fd:

[0137] 0 1 / 5 1 / 4 1 / 3 2 / 5 1 / 2 3 / 5 2 / 3 3 / 4 4 / 5 1

[0138] Table 2

[0139] More generally, for x cylinders evenly distributed around the shaft at a minimum operating speed r (revolutions per second), the repeating pattern every n cylinders will produce an oscillation with a frequency of xr / n.

[0140] By including each irreducible fraction m / n, where each m is at most n-1 and each n is at most a definite maximum value, a table with a larger maximum sequence length n can be generated.

[0141] A larger repeating pattern length (determined by n) will result in a proportionally lower frequency, but the table length will be larger.

[0142] For example, for n=12, the corresponding table would be:

[0143] 0 1 / 12 1 / 11 1 / 10 1 / 9 1 / 8 1 / 7 1 / 6 2 / 11 1 / 5 2 / 9 1 / 4 3 / 11 2 / 7 3 / 10 1 / 3 4 / 11 3 / 8 2 / 5 5 / 12 3 / 7 4 / 9 5 / 11 1 / 2 6 / 11 5 / 9 4 / 7 7 / 12 3 / 5 5 / 8 7 / 11 2 / 3 7 / 10 5 / 7 8 / 11 3 / 4 7 / 9 4 / 5 9 / 11 5 / 6 6 / 7 7 / 8 8 / 9 9 / 10 10 / 11 11 / 12 1

[0144] Table 3

[0145] In practice, the score can be stored in binary form, which will require some rounding based on the number of significant bits stored. Alternatively, the displacement score can be calculated without using a storage table.

[0146] It is worth noting that in these tables, the smallest non-zero fraction, and therefore the minimum value of Fd implemented by ECM, will be 1 / n, 1 / (n-1), 1 / (n-2)... (until the next number in the sequence is greater than or equal to 2 / n). The largest non-unit fractions are (n-1) / n, (n-2) / (n-1), and (n-3) / (n-2).

[0147] The maximum displacement band indicates the maximum displacement gap value appearing in the table, typically 1 / n. This provides a coarse indication of the quantized displacement step size and thus the acceptability of the quantization table. Very coarse displacement steps can hinder precise control of the actuator, which may be of particular concern in vehicle applications.

[0148] In the experiment, an excavator with an operator cab capable of oscillating at low frequencies (approximately 3 to 15 Hz) was used. The ECM-driven hydraulic actuator was fluidly connected to the ECM. The quantization table in Table 2 (maximum sequence length 12, i.e., n = 12) did not activate the cab but provided a sufficiently coarse displacement step size, resulting in an unacceptable user experience. Increasing the sequence length to 24, i.e., n = 24, did not activate the cab but provided a displacement step size with an acceptable user experience. Further increasing the sequence length to 36, i.e., n = 36, provided an acceptable step size, but the frequency content activated the cab.

[0149] Therefore, there is a trade-off between the minimum frequency and the roughness of the displacement level. In some applications, a clearance of up to 5% to 10% is acceptable. The clearance can be reduced by selecting an ECM with more working chambers at different phases, or by selecting a prime mover with a higher minimum shaft speed (or a constrained minimum shaft speed) and a higher maximum denominator.

[0150] While resonance within the cab itself is the primary concern in the specific case of hydraulic excavators, excitation and resonance from other objects are also noteworthy. For example, movement of the vehicle cab can cause resonance in a single operator, which in turn can lead to unintended movements of the control levers, potentially exacerbating the situation. This invention is particularly useful for avoiding low-frequency resonance effects.

[0151] In addition, some displacement scores may be deemed unacceptable, for example, due to the risk of triggering further resonance, and displacement scores deemed unacceptable can be removed from the displacement score table.

[0152] In the example in Table 1, the cylinders are equidistant in phase and there is no redundancy (n cylinders are constructed such that their volumetric cycles are spaced 360 / n° apart in phase). However, in known ECMs, the working chambers are not equidistant in phase and / or there is redundancy, referring to multiple working chambers that have the same phase as each other. The latter is common when the cylinders are driven by multi-leaf cams, for example, meaning that one or more working chamber cycles occur within a single rotation of the rotatable shaft. Non-uniform phase working chambers can occur due to the design of the ECM or due to the allocation of working chambers to different groups of working chambers during operation.

[0153] For example, the ECM has 24 cylinders with equal phase spacing (360 / 24 = 15°). Groups of three cylinders spaced 120° apart share a common high-pressure output, providing eight independent outputs. Three of these independent outputs are connected to the first high-pressure manifold, four of these independent outputs are connected to the second high-pressure manifold, and one independent output is connected to the third high-pressure manifold.

[0154] The phases of the nine cylinders connected to the first high-pressure manifold can be as follows:

[0155]

[0156] Table 4

[0157] Table 4 shows that in this embodiment, the phase between consecutive cylinder blocks is sometimes 30° and sometimes 60°. Therefore, there are unequal phases between the cylinder blocks.

[0158] In the example in Table 4, the repeating cylinder phase pattern length is 3. This number indicates how many cylinders are needed to repeat the cylinder phase. The phase difference between cylinder 1 and cylinder 2 is 30°. The phase difference between cylinder 2 and cylinder 3 is 30°. The phase difference between cylinder 3 and cylinder 4 is 60°. Then the pattern is repeated. Since repeating this pattern requires 3 cylinders, the repeating cylinder phase pattern length is 3.

[0159] The machine can also be designed with cylinder blocks that have repeating phases (redundancy). The table below shows a 6-cylinder machine with a redundancy of 2.

[0160] Number of cylinders 1 2 3 4 5 6 Phase (°) 0 0 120 120 240 240

[0161] Table 5

[0162] When creating the quantization table for such a machine, consideration should be given to ensuring that a maximum sequence length limits the minimum frequency requirement in the intended manner.

[0163] If all working chambers have a redundancy greater than 1, then the denominator of the fraction can be chosen as a multiple of the redundancy. Therefore, when the redundancy is 3, the table can include fractions such as 1 / 3, 1 / 6, 1 / 9, 1 / 12, 1 / 15, etc.

[0164] If the machine has unequally spaced working chambers, one option is to select all denominators that are multiples of the length of the repeating cylinder phase pattern. This will give the same minimum frequency as a machine with the same number of cylinders and equal spacing.

[0165] Therefore, in order to limit the minimum frequency, the permissible displacement level for machines or services with unequal phases or redundancy will be reduced. This will result in further coarsening in the quantization table.

[0166] The table below illustrates the effect of chamber redundancy in a 12-cylinder engine. It indicates which cylinders cycle effectively at 1 / 3 of the displacement fraction.

[0167]

[0168]

[0169] Table 6

[0170] Table 6 shows that when the redundancy is 1, there is a repeating pattern every 90° (i.e., the pattern repeats four times for every rotation of the rotatable shaft, thus four times the rotation frequency of the rotatable shaft); when the redundancy is 3, there is a repeating pattern every 90° (i.e., the pattern repeats four times for every rotation of the rotatable shaft, thus four times the rotation frequency of the rotatable shaft). However, when the redundancy is 2, the phase difference between the activated cylinders is sometimes 120 degrees, and sometimes 60 degrees. This results in a repeating pattern every 180° (i.e., the pattern repeats once for every half rotation of the rotatable shaft, thus twice the rotation frequency of the rotatable shaft); in the examples of redundancy 1 and redundancy 3, an activation fraction of 1 / 3 results in a frequency four times the shaft rotation frequency. An activation fraction of 1 / 3 results in a lower frequency of twice the shaft rotation frequency.

[0171] This example clearly shows that lower frequencies appear when the denominator is not an integer multiple of the redundancy in the quantization table. If the goal is to remove frequencies below twice the shaft rotation frequency, it is impossible to use the 1 / 3 enable fraction when the cylinder phase has a redundancy of 2.

[0172] In this case, the quantization table for embodiments with redundancy > 1 consists of fractions whose denominators are multiples of the redundancy. For example, for n to 18, calculate the following fractions, then sort them and remove duplicates: 1 / 3, 2 / 3, 3 / 3, 1 / 6, 2 / 6, 3 / 6, 4 / 6, 5 / 6, 6 / 6, 1 / 9, 2 / 9, 3 / 9, 4 / 9, 5 / 9, 6 / 9, 7 / 9, 8 / 9, 9 / 9, 1 / 12, 2 / 12, 3 / 12, 4 / 12, 5 / 12, 6 / 12, 7 / 12, 8 / 12, 9 / 12, 10 / 12, 11 / 12, 12 / 12, 1 / 15, 2 / 15, 3 / 15, 4 / 15, 5 / 15, 6 / 15, 7 / 15, 8 / 15, 9 / 15, 10 / 15, 11 / 15, 12 / 15, 13 / 15, 14 / 15, 15 / 15, 1 / 18, 2 / 18 3 / 18 4 / 18 5 / 18 6 / 18 7 / 18 8 / 18 9 / 18 10 / 18 11 / 18 12 / 18 13 / 18 14 / 18 15 / 18 16 / 18 17 / 18 18 / 18.

[0173] Reducing to irreducible fractions, we get:

[0174] Allowed Fd:

[0175] 0 1 / 18 1 / 15 1 / 12 1 / 9 2 / 15 1 / 6 1 / 5 2 / 9 1 / 4 4 / 15 5 / 18 1 / 3 7 / 18 2 / 5 5 / 12 4 / 9 7 / 15 1 / 2 8 / 15 5 / 9 7 / 12 3 / 5 11 / 18 2 / 3 13 / 18 11 / 15 3 / 4 7 / 9 4 / 5 5 / 6 13 / 15 8 / 9 11 / 12 14 / 15 17 / 18 1

[0176] Table 7

[0177] More generally, refer to Figure 6 The process of determining the quantization table begins with calculating 500 repeated cylinder patterns, which will depend on the relative phase difference of individual cylinders, and the existence and extent of redundancy between cylinders. Before operation (e.g. Figure 6 As shown, (e.g., through simulation or experiment), or during operation, broken cylinders can also be taken into account. In a simple example, with no redundancy and the phases of each cylinder equally separated, the repeating phase difference is simply the phase spacing between the cylinders. If the cylinder spacing is unequal, the repeating pattern should be calculated by identifying the number of cylinders required to generate the repeating phase difference pattern and then summing the phase differences between all cylinders. This is used to determine the phase difference between the repeating arrangements of the working chambers. In the examples in Tables 4 and 5, this is 120°. For a machine with c equidistant cylinders and a redundancy r, this is 360*r / c. The number of cylinders required to generate the repeating pattern is also determined. In the examples in Tables 4 and 5, this is 3.

[0178] In the next step, the permissible denominator for the 502 displacement fraction is calculated. This is done using the minimum expected operating shaft speed and the phase difference between the number of cylinders and the cylinder repetition pattern calculated in the previous step, and this step also includes the minimum acceptable frequency. Thus, it is possible to calculate the permissible denominator for the repetition pattern that will not result in a frequency lower than the minimum frequency. Figure 6 In the example, the redundancy is 3, the shaft speed is 1500 rpm, the minimum frequency is 15 Hz, and the allowed denominators are 3, 6, 9, 12, and 15.

[0179] Subsequently, the allowable Fd values ​​for 504 are calculated using these denominators (i.e., the displacement fraction chosen as one of the available quantifications). Typically, for each allowable denominator n, the quantification table will include each m / n, where for each value of n, m is each integer from 1 to n.

[0180] Next, the calculated scores are processed by removing duplicates 506 and sorting them in numerical order. In an optional next stage, some Fd values ​​can be filtered out of the calculated list (508 is removed from the list) because they can produce some other resonances, such as the resonance of another part of the device.

[0181] Subsequently, there is a verification step 510, in which the calculated allowable Fd values ​​are analyzed to determine whether they provide a sufficiently smooth operation for the user.

[0182] The final set of calculated FD values ​​is then stored in memory and used during machine operation. As mentioned above, different allowable Fd tables may exist for different shaft speeds or operating modes of the equipment, such as when different groups of working chambers are connected to separate high-pressure manifolds.

[0183] In the example above, the device controller 100 has already created a quantified demand signal and avoided generating repetitive patterns of cylinder activation exceeding a predetermined length, without requiring modification to the ECM controller 50 or changing its algorithm (Sigma-Delta (∑-Δ) algorithm). Therefore, to achieve the desired displacement, the precise number of cylinders actually causing an effective cycle is determined by the ECM controller. Typically, these are not predetermined and will vary in different applications depending on the time history of shaft rotation and the desired displacement.

[0184] As explained, for electro-reversing hydraulic presses, it is generally advantageous to distribute the effective and ineffective cycles of the working chamber volume to meet segmented displacement requirements, and typically each effective cycle has the same net displacement, which is the maximum net displacement of each working chamber. However, referring to... Figures 7A to 7C An embodiment will now be described in which the stroke volume of the working chamber during an effective cycle is reduced by modifying the valve timing. While this may be less efficient in some respects, it can be combined with the quantization methods discussed above to produce a reliable machine that suppresses the generation of undesirable, such as low-frequency vibrations, which can provide a wide (and in some embodiments) continuous range of displacement fraction.

[0185] In these embodiments, by altering the timing of the active control of the low-pressure and high-pressure valves, the net displacement during the effective cycle is reduced to below 100% of the maximum displacement. The method for doing so is known from WO2004 / 025122. For example, during a pumping cycle, the closing time of the low-pressure valve may be delayed from its normal phase, i.e., shortly after the point of maximum cylinder volume (top dead center). For a short delay, this results in a slight reduction in displacement. If the closing of the low-pressure valve is delayed to near the point of minimum cylinder volume (top dead center), the displacement will be reduced to a fraction of the maximum displacement. In the case of a motorized cycle, during the expansion stroke (from top dead center to bottom dead center), the low-pressure valve opens earlier and the high-pressure valve closes earlier compared to other cases, reducing the volume of working fluid received from the high-pressure manifold. This step typically occurs late in the expansion stroke; advancing it slightly forward results in a slight reduction in displacement, while advancing it shortly after the point of minimum cylinder volume results in a significant reduction in net displacement.

[0186] In operation, for any given value of the received (e.g., calculated or input) displacement demand Fd (x-axis), Fd is multiplied by a scaling factor of 406, which is designed to ensure that the selected quantified displacement fraction is always greater than the demand, so that the actual required displacement can still be achieved by reducing the volume delivered per cylinder (by adjusting valve timing). Figure 7A and 7B Use a scaling factor. For example... Figure 7A As shown, the fraction of cylinders performing effective cycles is quantized as previously described, thereby suppressing the generation of unwanted frequency components. However, valve timing is modified to make the total net displacement closer to the desired displacement. It is desirable to keep the stroke dimension of each cylinder as close to 100% as possible; to achieve this, the scaling factor used for "rounding" the displacement must itself be a function of Fd, as... Figure 7C As shown. By using this type of function, the quantized Fd can be kept at a level that is approximately fixed above the Fd requirement, thus ensuring that the stroke size is maximized.

[0187] As an example, Figure 7B The 0.9 on the y-axis corresponds to the net displacement per cylinder block, which is 90% of the delivery volume when using a full stroke (maximum stroke). As a result of the cylinder block enablement algorithm, the quantification of displacement demand helps control the frequency content of the machine's output, and from Figures 7A to 7C As can be seen on the left, under low displacement requirements, the cylinder activation frequency does not drop below a threshold (approximately 0.1); instead, partial stroke capacity decreases. This avoids the generation of pulse patterns with very low frequency content while still allowing the output displacement to closely match the input displacement requirement. A similar effect can be seen under high displacement requirements, where this method avoids the generation of low-frequency patterns that cause cylinder failure.

[0188] As shown in the image above and Figure 7A As shown, the quantization requirement sent to the ECM controller 50 is always higher than the continuous displacement requirement. This requires that the effective cycle fraction of the quantization be higher than the continuous displacement requirement, meaning that the partial stroke size can be 1 or lower to accurately achieve the continuous displacement requirement. If the quantization requirement is lower than the continuous displacement requirement, then the partial stroke size required to achieve continuous displacement must be greater than 1, which is impossible.

[0189] While it's possible to leave unmet gaps within a displacement range, these gaps can be avoided by ensuring that the quantified demand signal is greater than the continuous displacement demand across the entire displacement range. In this example, this is achieved by multiplying the continuous displacement demand by... Figure 7C The scaling factor shown is used to achieve this, but it is not the only possible method. For example, a bias can be applied to continuous demand, and this can also be varied across the entire displacement range.

[0190] In alternative embodiments, the gap is addressed by selecting the discrete effective cycle fraction that best approximates the continuous displacement requirement and by applying only downward hysteresis instead of upward hysteresis. These methods prevent the requirement to enable a partial stroke fraction higher than 1 in the cylinder block. For the reasons mentioned above, it is preferable, throughout the displacement range, that the partial stroke size is as close as possible to the full stroke size.

[0191] When the required displacement is noisy, hysteresis can prevent jumps between quantization steps. Figure 7A In the scenario shown, where the Fd (linear continuous displacement demand) signal is smooth, hysteresis (or scaling) can be omitted, and it is sufficient to round it to the nearest quantization step size higher than the (linear continuous displacement demand) Fd. Unfortunately, in reality, the demand signal will contain noise, thus requiring some hysteresis, which means determining the threshold difference between changing the step size upwards and downwards. If noise is present, applying hysteresis to the quantizer can prevent switching back and forth between step sizes, provided there is sufficient hysteresis. If the noise level is greater than the step size itself, then the amount of hysteresis alone will not help.

[0192] An alternative, and perhaps better, approach is to use recoil. Recoil prevents the output signal from changing sign when the rate of change of the input signal changes. This typically has a single parameter called the "dead band," which is the amount of difference between the input and output that causes the output to start following the input again. This type of signal processing often results in an offset between the input and output signals. This offset can be corrected using scaling, such as... Figure 7C As shown in the diagram. The scaling function is of type y = n / x + 1, where n is half the dead zone width.

[0193] In the example above, the discrete values ​​in the quantization table correspond to the discrete fractions of the working chambers that will perform effective cycles of the working chamber volume. This is because the demand signal is measured in displacement fractions. However, this is not necessary.

[0194] Further variations and modifications can be made within the scope of the invention disclosed herein.

Claims

1. A method for operating a hydraulic device, the hydraulic device comprising: Prime mover and multiple hydraulic actuators; A hydraulic press having a rotatable shaft driven and engaged with a prime mover and including a plurality of working chambers having a volume that cyclically changes with rotation of the rotatable shaft. A hydraulic circuit extending between a group of one or more working chambers of the hydraulic press and one or more of the hydraulic actuators. Each working chamber of the hydraulic press includes a low-pressure valve and a high-pressure valve. The low-pressure valve regulates the flow of hydraulic fluid between the working chamber and the low-pressure manifold, and the high-pressure valve regulates the flow of hydraulic fluid between the working chamber and the high-pressure manifold. The hydraulic mechanism is configured to actively control at least the low-pressure valves of the group of one or more working chambers in response to a demand signal, to select the net discharge rate of the hydraulic fluid in each working chamber on a circulation of each working chamber volume, and thereby select the net discharge rate of the hydraulic fluid in the group of one or more working chambers. The method includes controlling the low-pressure valve and the high-pressure valve to cause each working chamber to perform an effective or ineffective cycle of the working chamber volume during each cycle of the working chamber volume. Its characteristic is that the fraction of working chambers performing effective cycles is variable and selected from multiple discrete fractions. Specifically, the plurality of discrete fractions are selected to avoid generating any repeating patterns of valid and invalid cycles with a length greater than the predetermined maximum repeating pattern length of the working chamber volume.

2. The method according to claim 1, characterized in that, When represented as irreducible fractions, the plurality of discrete fractions do not include any fractions whose denominators are greater than a predetermined maximum denominator.

3. The method according to claim 1, characterized in that, The demand signal responded to by the hydraulic press is quantized and has one of a plurality of discrete values.

4. The method according to claim 2, characterized in that, The discrete fraction is represented as an irreducible fraction, and the range of the denominator can reach the maximum value. The maximum value is selected to avoid generating repetitive patterns of working chamber actuation with a frequency lower than a predetermined minimum value.

5. The method according to claim 1, characterized in that, The smallest non-zero fraction among the plurality of discrete fractions is 1 / n, and typically the second smallest fraction among the plurality of discrete fractions is 1 / (n-1), where n is an integer.

6. The method according to claim 1, characterized in that, Considering the case where two or more working chambers have the same phase or there is a non-uniform phase difference between two or more working chambers, the smallest non-zero fraction among the plurality of discrete fractions is selected.

7. The method according to claim 1, characterized in that, The discrete fractions are determined through simulation or experimentation, typically wherein, in response to the simulation or experimentation, the discrete fractions are included among the plurality of discrete fractions, wherein the simulation or experimentation shows that the frequency components of the obtained high-pressure manifold pressure or valve activation current meet one or more acceptable spectral criteria, and / or wherein the frequency content below the cutoff frequency is below a threshold, or wherein the effect of selecting effective and ineffective cycles is found to be acceptable, or if they do not meet such criteria, they are excluded.

8. The method according to claim 3, characterized in that, The discrete fractions and / or the plurality of discrete values ​​of the quantized demand signal are calculated during operation and / or calculated in real time taking into account predetermined parameters and / or current measurement parameters.

9. The method according to claim 1, characterized in that, The plurality of discrete fractions respond to changes in the rotational speed of the rotatable shaft.

10. The method according to claim 9, characterized in that, The method includes switching from using a first plurality of discrete fractions to a second plurality of discrete fractions when the rotational speed of the rotatable shaft exceeds a threshold.

11. The method according to claim 1, characterized in that, Adjust the opening or closing time of at least the low-pressure valve to change the fraction of the maximum stroke volume discharged from each working chamber during each effective cycle.

12. The method according to claim 11, characterized in that, Although the fraction of the working chambers performing effective cycles is limited to one of the plurality of discrete fractions, this enables the rotatable shaft to produce a continuous range of displacement per revolution.

13. A method for calculating a plurality of discrete fractions, for use in the method according to any one of claims 1 to 12, the method comprising: Input the minimum allowable frequency, the target operating speed of the rotatable shaft, and data indicating the number and / or phase difference between the machine's working chambers, and / or the phase difference between groups of working chambers; Calculate the integer number n of working chamber decision points between effective cycles, which will result in a cylinder activation frequency that exceeds only the minimum permissible frequency, and include 1 / n in the plurality of discrete fractions.

14. The method according to claim 13, characterized in that, It also includes, after removing duplicate values, a plurality of discrete fractions comprising fractions in which the denominator is an integer of at most n and the numerator is an integer of at most n-1.

15. The method according to claim 13 or claim 14, characterized in that, This includes removing one or more discrete fractions from the plurality of discrete fractions to avoid generating repetitive cylinder activation patterns with frequency components below a specific value.

16. The method according to any one of claims 11 to 14, characterized in that, It also includes storing the plurality of discrete fractions on a solid-state storage device for retrieval during operation.

17. A solid-state storage device that stores a plurality of discrete fractions calculated by the method of claim 16.

18. A method for calculating a plurality of discrete fractions for use in the apparatus of claim 17, the method comprising: Input the minimum allowable frequency, the target operating speed of the rotatable shaft, and data indicating the number and / or phase difference between the machine's working chambers, and / or the phase difference between groups of working chambers; Calculate the integer number n of working chamber decision points between effective cycles, which will result in a cylinder activation frequency that exceeds only the minimum permissible frequency, and include 1 / n in the plurality of discrete fractions.

19. A hydraulic device, the device comprising: Prime mover and multiple hydraulic actuators; A hydraulic press having a rotatable shaft driven and engaged with a prime mover, and including a plurality of working chambers having a volume that cyclically changes with rotation of the rotatable shaft. A hydraulic circuit extending between a group of one or more working chambers of the hydraulic press and one or more of the hydraulic actuators. Each working chamber of the hydraulic press includes a low-pressure valve and a high-pressure valve. The low-pressure valve regulates the flow of hydraulic fluid between the working chamber and the low-pressure manifold, and the high-pressure valve regulates the flow of hydraulic fluid between the working chamber and the high-pressure manifold. The hydraulic press includes a controller configured to actively control at least the low-pressure valves of the group of one or more working chambers in response to a demand signal, to select the net discharge rate of the hydraulic fluid in each working chamber on a circulation of each working chamber volume, and thereby select the net discharge rate of the hydraulic fluid in the group of one or more working chambers. The controller is configured to control the low-pressure valve and the high-pressure valve so that each working chamber performs an effective or ineffective cycle of the working chamber volume during each cycle of the working chamber volume. The device is characterized in that the fraction of the working chambers performing effective cycles is variable, and a plurality of discrete fractions are selected, wherein the plurality of discrete fractions are selected to avoid generating any repeating patterns of effective and invalid cycles with a length greater than a predetermined maximum repeating pattern length in the working chamber volume.

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