JP2020197304A - Hydraulic machines and systems - Google Patents

Abstract

To provide a hydraulic system employing an electronically commutated hydraulic machine capable of reducing or mitigating the possibility of leading to vibration, discomfort to users and a risk of damage to the machine.SOLUTION: A high-pressure manifold 166, 168, 170 has at least one additional outlet, regulated by an electronically controllable outlet valve 190 such as a proportional flow valve. If a demand indicated by a demand signal is expected to cause a pulsatile flow or vibrations which may excite resonant modes, at least one controller 158 causes displacement of working fluid by working chambers to exceed the demand indicated by the demand signal, and the at least one controller simultaneously (at least partially) opens an electronically controllable outlet valve to allow some of the excess flow to leave, so that the net displacement of fluid meets the demanded displacement of the fluid while mitigating the pulsatile flow or undesirable vibrations.SELECTED DRAWING: Figure 3

Description

The present invention relates to electronically rectified hydraulic machines and the field of hydraulic systems including such machines.

Electronic rectifying hydraulic machines (ECMs) include fluid driven and / or fluid driven machines with one or more working chambers (eg, piston cylinders) that periodically change volume. When the working chamber performs a pumping cycle, the low pressure manifold acts as a net fluid source and the high pressure manifold acts as a net fluid sink. When the working chamber performs the motoring cycle, the high pressure manifold acts as a net fluid source and the low pressure manifold acts as a net fluid sink. The ECM may include two or more low pressure manifolds and / or two or more high pressure manifolds.

The ECM work chamber has an electronically controllable valve, which is controlled in each cycle of the work chamber volume to enter and exit the work chamber and into and out of the low pressure manifold and, in some embodiments, the high pressure manifold. The flow of fluid can be adjusted.

In some ECMs, there is a single high pressure manifold in which all working chambers communicate with it to allow fluid to move in and out of the high pressure manifold to meet demand. However, there are multiple high pressure manifolds communicating with different groups of one or more work chambers, each group being controlled in response to a separate request signal, so that the combined displacement of the work chambers within the group is required. Can be met. For this reason, individual groups of working chambers may function as independent pumps or motors.

The request (s) are represented by a request signal (s) that can indicate the target pressure, flow rate, output, or characteristic (eg, position) of the hydraulic actuator directly or indirectly coupled to the associated high pressure manifold. .. To meet the requirement, the ECM controller should make each cycle of the working chamber volume an active cycle with a net displacement of the working fluid or an inactive cycle with no net displacement of the working fluid. Make a decision about. This leads to a working chamber operating pattern (active or inactive cycle) and a pattern of inflow to or out of the respective high pressure manifold. In this way, changes in requirements can be responded quickly. Normally, the output does not exactly match the request from one moment to the next, but on a short-term average, the net output addresses the request. Such machines are efficient and responsive.

However, depending on the cylinder operation pattern, vibration may occur in the hydraulic machine. Depending on the frequency of vibration, the resonant mode may be excited within the hydraulic machine, which can cause damage to mechanical components and discomfort to the user. This can occur when the frequency spectrum of the pattern of whether the working chamber performs active or inactive cycles has a large component at frequencies where resonance can be excited to meet the requirement.

At low flow levels, fluid displacement can be very pulsating. When the output is 5% of the maximum displacement rate, the active cycle pattern is repeated every 20 cycles, and there is an inactive cycle in between. This can also lead to the risk of vibration, user discomfort, and machine damage. Similarly, when operating a hydraulic machine at a low flow rate, the operation can be inefficient.

Therefore, the present invention seeks to reduce or alleviate some or all of the above drawbacks of existing electronically rectified hydraulic machines.

According to the first aspect of the present invention, a hydraulic system is provided.
A hydraulic machine comprising a rotatable shaft, a low pressure manifold and a high pressure manifold, and one or more working chambers having a volume that changes cyclically with the rotation of the rotatable shaft, each working chamber with a low pressure manifold. It has both a low pressure valve that regulates the communication with the work chamber and a high pressure valve that regulates the communication between the high pressure manifold and the work chamber, and for each work chamber, each low pressure valve and its own high pressure. Hydraulic machinery, where at least one of the valves is an electronically controllable work chamber valve,
A high pressure manifold extending between one or more of the above working chambers, one or more actuator ports and one or more additional outlets.
With one or more hydraulic actuators fluidly connected to the high pressure manifold through one or more actuator ports and thus hydraulically driven by a hydraulic machine.
With one or more electronically controllable outlet valves that regulate the opening or closing of one or more additional outlets,
It comprises one or more electronically controllable work chamber valves and at least one controller configured to control one or more electronically controllable outlet valves.
At least one controller receives the request signal and adjusts one or more electronically controllable work chamber valves in phase with respect to the cycle of the work chamber volume, thereby each work chamber in each cycle of the work chamber volume. It is possible to adjust the net displacement of the working fluid by and to adjust one or more electronically controllable outlet valves at the same time, thereby opening one or more additional outlets. Through the above additional outlets, the net displacement of the working fluid to or from the high pressure chamber that allows the flow of the working fluid from the high pressure chamber is adjusted to meet the requirements indicated by the request signal.

Thus, the loss of hydraulic fluid through one or more additional outlets is regulated by at least one controller and the net working fluid to and from the high pressure manifold (during pumping) or from the high pressure manifold (during motoring). The displacement is adjusted to meet the requirements, taking into account both the net displacement of the working fluid by each working chamber and the loss of hydraulic fluid through one or more additional outlets (s). The high pressure manifold comprises one or more actuator ports connected to one or more actuators, which serve as sinks or sources of hydraulic fluid. Normally, fluid flowing out of one or more additional outlets does not move between the work chamber and the actuator port. Normally, fluid flowing out of one or more additional outlets bypasses one or more actuators connected to the actuator port (although in some embodiments, one or more additional outlets). Pressurized fluid lost through is used to drive one or more other actuators to minimize wasted energy). Typically, the requirement relates to the supply of hydraulic fluid through one or more actuator ports between the working chamber (s) and the actuators (s).

The types of hydraulic machines described have very fast response times to changing demands because they can control electronically controllable valves to change the net displacement of the working fluid for each cycle of working chamber volume. Therefore, in many cases, the net displacement of the working fluid by the continuous working chamber is matched to the time-varying demand signal. In addition, by providing one or more additional outlets (s), working fluid (eg, excess) can be lost from the high pressure manifold, appearing to be wasting energy. Therefore, it is incompatible with intuition.

Within the scope of this description and the appended claims, the terms "high pressure manifold" and "low pressure manifold" refer to manifolds that have higher and lower pressures relative to each other. The pressure difference between the high pressure manifold and the low pressure manifold, and the absolute value of the pressure in the high pressure manifold and the low pressure manifold will change over time and will vary from application to application.

In some embodiments, at least one controller controls an electronically controllable working chamber valve to cause the hydraulic machine to displace the working fluid beyond the requirements indicated by the request signal, one or more (or all). The net displacement of the working fluid from one or more working chambers through the high pressure valve into the high pressure manifold, thereby opening the working fluid from the high pressure manifold through one or more additional outlets. After allowing the outflow of the fluid, it is adjusted to meet the requirements indicated by the request signal.

Allowing the flow of working fluid out of the high pressure manifold through one or more additional outlets (eg, with at least one controller),
i) Compute a modified request signal tuned for flow out of the high pressure manifold through one or more additional outlets, or ii) High pressure through one or more additional outlets. It may include subtracting requirements for the flow of working fluid out of the manifold.

The flow is under the control of at least one controller because at least one controller controls one or more electronically controllable outlet valves. At least one controller controls an electronically controllable work chamber valve to displace the working fluid beyond the requirements indicated by the request signal, and one or more outlet valves in some situations. It may be configured to open only. At least one controller can also take into account any expected leakage from the high pressure manifold. Such leaks can result from control valves (eg, in wheel motors, or for controlling other actuators and / or working functions). Thus, the one or more electronically controllable work chamber valves and the one or more electronically controllable outlet valves are controlled to meet the requirements indicated by the request signal.

Usually, at least one controller, under some other circumstances, usually by default, controls the electronically controllable working chamber valve so that the hydraulic machine matches the requirements indicated by the request signal. Is configured to displace and close the outlet valve so that the working fluid does not flow out of the high pressure manifold through the additional outlet.

In some embodiments, the one or more outlet valves (s) (eg, said or each outlet valve) are variable flow control valves, such as, for example, proportional flow valves, and at least one controller is located. Control the variable flow control valve over the range of.

In this case, the range of positions is usually continuous. The or each outlet valve is usually controlled to a plurality of positions, eg, a continuous range, between the closed position and the fully open position. Opening refers to any position that is not closed.

Adjustment of the position of one or more (or such or each) outlet valves may occur out of phase with the cycle of the working chamber volume. It can take longer than the working chamber volume cycle for the outlet valve to open or close. The outlet valve can remain open for 10 or more cycles, or 100 or more cycles, of the working chamber volume on average (midpoint).

However, in some embodiments, at least one controller is configured to open and close the outlet valve in phase with respect to the cycle of working chamber volume. In this case, the outlet valve is usually a solenoid valve that is actively controlled to move directly from an open position to a closed position and vice versa without stopping. For this reason, it is either open, closed, or moving between these positions (on-off valve) and is maintained in a variable position between the open and closed positions ( And is not a proportional flow valve configured to be maintained during use). Therefore, using the on / off valve, the flow through the outlet valve is regulated by opening and closing the valve, for example, by adjusting the percentage of time the outlet valve is open. The outlet valve can have an opening and closing time of less than 10 ms, preferably less than 5 ms. The outlet valve is typically open to pressure differences.

In this case, the timing of opening and closing the outlet valve can be controlled by at least one controller to reduce (eg, selectively) the pressure ripple in the high pressure manifold. This is when the displacement of the hydraulic machine is below the threshold, for example, less than 10% or less than 5% of the maximum displacement of the hydraulic fluid by the hydraulic machine per rotation of the rotatable shaft, and / or the high pressure manifold and /. Or when a peak of pressure in the Soliton is detected or predicted (eg, as a result of a pattern of active and inactive cycles of working chamber volume determined by at least one controller in response to a request signal), and / Or it can occur when the ratio of the working chamber volume to the active cycle to the inactive cycle can be below the threshold, i.e. 1: 9 or less. This can be considered as a ripple reduction operating mode for at least one controller. The ripple reduction operating mode of at least one controller functions to attenuate the pressure pulse in the high pressure manifold.

Typically, at least one controller is configured to open and close the outlet valve once per active cycle of working chamber volume in ripple reduction operating mode. Typically, at least one controller is configured such that each opening and subsequent closure of at least one outlet valve overlaps a single cycle of working chamber volume. Normally, the outlet valve is opened before the peak of fluid pressure resulting from the active cycle of the working chamber volume and closed after the peak of fluid pressure resulting from the active cycle of the working chamber volume. Opening and closing the outlet valve can have the effect of reducing or clipping the peak pressure resulting from the individual active cycles of the working chamber. Opening and closing the outlet valve can have the effect of reducing the pressure ripple resulting from the individual active cycles of the working chamber. If at least one controller has a high ratio of normally active cycles to inactive cycles, eg, above a threshold, i.e. 9: 1, in at least some situations, the outlet valve is (throughout a continuous active cycle). ) It remains open, but may be configured to be reopened during an inactive cycle after closing. This reduces pressure ripple in these situations because the pressure is maintained during the inactive cycle when the majority of the cycle is the active cycle.

In some embodiments, the high pressure manifold communicates through an inlet valve with a higher pressure working fluid source (ie, a source having a working fluid at a higher pressure than the high pressure manifold, such as an accumulator or a higher pressure manifold). At least one controller is configured to close and open the inlet valve in phase with the cycle of the working chamber volume to reduce pressure ripple. In this case, the working fluid can enter the high pressure manifold (from the high pressure working fluid source) at least occasionally through the inlet valve, and the supply of this working fluid during the active cycle of the working chamber volume (closes the inlet valve and then). It will be temporarily closed (by opening it again). Thus, the additional flow of working fluid compensates for shortages or deletions in the supply of working fluid during the active cycle of working fluid and reduces pressure ripple. The inlet valve is typically closed before the maximum fluid flow point during the working chamber volume cycle and reopened after the point of maximum fluid flow during the working chamber volume cycle. This ripple reduction mode is used when the displacement of the hydraulic machine is below the threshold, for example, less than 10% or less than 5% of the maximum displacement of the hydraulic fluid by the hydraulic machine per rotation of the rotatable shaft, and / or high pressure. When a peak of pressure in the manifold and / or soliton is detected or predicted (eg, as a result of a pattern of active and inactive cycles of working chamber volume determined by at least one controller in response to a request signal). , And / or when the ratio of active cycle to inactive cycle of working chamber volume can be below the threshold, i.e. 1: 9 or less. The inlet valve may remain closed when at least one controller is not in ripple reduction mode. When at least one controller is in ripple reduction mode, the inlet valve may be opened by default, closed and reopened by at least one controller once per active cycle of working chamber volume.

At least one controller sends a pulse width modulated signal (usually producing the corresponding solenoid current) to the outlet (and / or inlet) valve (eg, the solenoid actuator of the outlet valve) to the outlet (and / or inlet). ) Valve opening and closing may usually be actively controlled in phase with respect to the cycle of working chamber volume.

At least one controller has (a) the required signal, (b) the volume of working fluid displaced by the hydraulic machine per rotation and / or second of the rotatable shaft, and (c) the rotational speed of the rotatable shaft. , (D) High pressure manifold compatibility (variation of system pressure due to volume of working fluid in the high pressure manifold), (e) For example, at least one controller requires in feedback, feed forward, and / or open loop control modes. Outlet (and / or inlet) in response to one or more measurements or calculations of the operating mode of the hydraulic system, (f) the temperature of the working fluid, whether to adjust the displacement in response to the signal. The timing of valve opening and / or closing can be varied in phase with respect to the cycle of working chamber volume.

In some embodiments, the one or more additional outlets extend from the high pressure manifold to the low pressure manifold, so that the one or more outlet valves are through the one or more additional outlets of the high pressure manifold. Regulates the flow of working fluid from the low pressure manifold.

If necessary, one or more additional outlets extend from the high pressure manifold to the additional manifold so that each one or more outlet valves from the high pressure manifold through one or more of the additional outlets. Adjust the flow of working fluid to additional manifolds.

In some embodiments, the additional manifold is a pressurizing manifold, eg, a manifold that communicates fluidly with one or more (usually other) actuators. This arrangement retains, at least partially, the potential energy stored in the working fluid flowing from the high pressure manifold to the additional pressurized manifold that communicates with one or more actuators (usually the other). It is advantageous because it is (and can be used to optionally work). The additional manifold may be a boost line to a hydraulic motor or other actuator. The boost line provides the minimum back pressure required for the actuator. This boost line may be connected to the low pressure port of the hydraulic steering mechanism.

In some embodiments, the one or more additional outlets (s) are one or more compliant regions from which the energy from the pressurization of the working fluid can be stored as potential energy from the high pressure manifold. For example, it extends to additional manifolds with flexible hoses or accumulators (s).

If desired, the high pressure manifold may be part of a closed circuit hydraulic arrangement, and additional manifolds may be part of an open circuit hydraulic arrangement and vice versa.

Typically, the hydraulic system is equipped with a prime mover coupled to the hydraulic machine to provide the hydraulic machine with power to pump the working fluid from the low pressure manifold to the high pressure manifold, and the hydraulic system pumps the working fluid from the low pressure manifold ( Further comprising a prime mover configured to pump from the same or another low pressure manifold) to an additional manifold, or a second hydraulic machine driven by one or more additional working chambers of the (first) hydraulic machine. As such, the prime mover powers both open and closed circuit hydraulic arrangements (ie, the high pressure manifold is part of the open circuit, the additional manifold is part of the closed circuit, and vice versa. Is).

The hydraulic machine may be one or more electronic rectifying machines (ECMs). An ECM is a rotatable shaft and one or more working chambers having a volume that changes cyclically with the rotation of the rotatable shaft (eg, defined by a cylinder, in which the piston reciprocates during use. A moving chamber) and a hydraulic fluid actuating machine, including a low pressure valve that regulates the flow of hydraulic fluid between the work chamber and the low pressure manifold, and the hydraulic pressure between the work chamber and the high pressure manifold. It has a high pressure valve that regulates the flow of fluid. The reciprocating motion of the piston can be caused by an eccentric on a rotatable shaft, or direct interaction with a second rotatable shaft, the second rotatable shaft being rotatable into a rotatable shaft. Connected to. Multiple ECMs linked with rotatable shafts (eg, common shafts) driven by a prime mover can function together as a hydraulic machine.

The flood control system can be a flood control vehicle, typically an industrial or off-highway vehicle, such as a forklift truck.

The capabilities of the various components will be selected according to the application. In one example, the electronically controllable outlet valve may be configured to allow a flow rate of at least 20 liters per minute, or at least 25 liters per minute. The electronically controllable outlet valve may be configured to allow a rated flow rate of 15 liters per minute.

The electronically controllable outlet valve can be a solenoid operated (eg, electrically proportional) flow control valve. The electronically controllable outlet valve can be an electromagnetically proportional valve. Alternatively, a manually adjustable flow control valve or orifice can be used in combination (usually in series) with an electrically controllable on / off valve, both of which can function as an electronically controllable outlet valve. ..

The at least one controller typically comprises one or more hardware processors that together process the request signal and control one or more electronically controllable outlet valves. Typically, the first hardware processor determines both the net displacement of one or more working chambers and the intended flow of hydraulic fluid out of one or more outlets. One or more second hardware processors may generate control signals that actively control electronically controllable work chamber valves. The first hardware processor receives the request signal and sends one or more regulated request signals (taking into account the flow of working fluid out of the high pressure manifold through one or more outlet valves). It can be sent to a second hardware processor. The second hardware processor or each second hardware processor actively controls an electronically controllable work chamber valve to displace the working fluid by one or more work chambers as indicated by a tuned request signal. Can generate valve control signals to carry out.

A second aspect of the present invention provides a method of operating a hydraulic system, wherein the hydraulic system is a hydraulic machine, periodic with rotation of a rotatable shaft, a low pressure chamber and a high pressure manifold, and a rotatable shaft. It comprises one or more working chambers with varying volumes, each working chamber adjusting the low pressure valve that regulates the communication between the low pressure manifold and the working chamber, and the communication between the high pressure manifold and the working chamber. A hydraulic machine having a high pressure valve, for each work chamber, at least one of each low pressure valve and high pressure valve is an electronically controllable work chamber valve.
A high pressure manifold extending between one or more of the above working chambers, one or more actuator ports and one or more additional outlets.
With one or more hydraulic actuators fluidly connected to the high pressure manifold through one or more actuator ports and thereby driven hydraulically by a hydraulic machine.
With one or more electronically controllable outlet valves, which regulate the opening or closing of one or more additional outlets.
The method receives a request signal and in response adjusts one or more electronically controllable working chamber valves in phase with respect to the cycle of the working chamber volume, thereby each of the working chamber volumes. When adjusting the net displacement of the working fluid by each working chamber in a cycle and simultaneously adjusting one or more electronically controllable outlet valves, thereby opening one or more additional outlets, 1 To meet the requirements indicated by the request signal by adjusting the net displacement of the working fluid to or from the high pressure chamber that allows the flow of the working fluid from the high pressure chamber through one or more additional outlets. And, including.

In some embodiments, the electronically controllable work chamber valve is controlled so that the hydraulic machine displaces the working fluid beyond the requirements indicated by the request signal, and one or more electronically controllable outlet valves. The net displacement of the working fluid from one or more working chambers to the high pressure manifold is controlled so that the working fluid flow out of the high pressure manifold through one or more additional outlets. After making it possible, it is adjusted to meet the requirements indicated by the request signal.

Under some other circumstances, usually by default, an electronically controllable work chamber valve is controlled to displace the working fluid so that the hydraulic machine meets the requirements indicated by the request signal, one or more. The outlet valve is closed so that the working fluid does not flow out of the high pressure chamber through one or more additional outlets.

The request signal may include or be used to calculate the maximum displacement factor (Fd). Typically, the displacement converted to volumetric flow rate is proportional to the maximum displacement rate and the rotational speed of the rotatable shaft. If desired, the request signal may be a tuned request signal, for example, at least one controller has received the request signal and determined that the received request signal is associated with a pulsatile flow. If so, a tuned request signal (usually a request signal indicating a higher required flow rate) can be calculated.

In some embodiments of the method, when the requirement is below the threshold, the electronically controllable working chamber valve directs the working fluid to the hydraulic machine at a given minimum rate of maximum displacement, or the active or inactive cycle of the working chamber volume. Can be controlled to displace in a predetermined pattern of the working chamber to perform
One or more outlet valves are controlled to drain the hydraulic fluid from the high pressure manifold so that the overall displacement of the working fluid into the high pressure manifold meets the requirements.

This helps to avoid the undesired effects of high pulsatile flow that occur at low requirements, for example, when requirements are met using only irregular active cycles of working chamber volume.

Normally, at least one controller (eg, towards the lower end of the operating range of the flow rate) requests an idle cycle with no net displacement of the fluid and a partial cycle in which part of the maximum stroke volume of the working chamber is displaced. Can be operated to be scattered even if is constant. Typically, within a portion of the flow operating range, at least one controller has an idle cycle with no net displacement of the fluid, a partial cycle in which part of the maximum stroke volume of the work chamber is displaced, and a maximum stroke volume of the work chamber. It is possible to operate the full cycle in which the is displaced so as to be scattered even when the request signal remains constant.

At least one outlet valve can be opened and closed out of phase with the cycle of the working chamber volume. The outlet valve can remain open for 10 or more cycles, or 100 or more cycles, of the working chamber volume on average (midpoint). However, this method may include opening and closing the outlet valve in phase with respect to the working chamber cycle.

In this case, the timing of opening and closing of the outlet valve can be controlled to (eg, selectively) reduce the pressure ripple in the high pressure manifold. This is when the displacement of the hydraulic machine is below the threshold, for example, less than 10% or less than 5% of the maximum displacement of the hydraulic fluid by the hydraulic machine per rotation of the rotatable shaft, and / or the high pressure manifold and /. Or when a peak of pressure in the Soliton is detected or predicted (eg, as a result of a pattern of active and inactive cycles of working chamber volume determined by at least one controller in response to a request signal), and / Or it can occur when the ratio of the working chamber volume to the active cycle to the inactive cycle can be below the threshold, i.e. 1: 9 or less. This can be considered as a ripple reduction operating mode that attenuates the pressure pulses in the high pressure manifold.

The outlet valve may be opened and closed once per active cycle of working chamber volume (in ripple reduction operating mode). Normally, each opening and subsequent closing of at least one outlet valve overlaps with a single cycle of working chamber volume. Normally, the outlet valve is opened before the peak of fluid pressure resulting from the active cycle of the working chamber volume and closed after the peak of fluid pressure resulting from the active cycle of the working chamber volume.

In some embodiments, the high pressure manifold communicates with a higher pressure working fluid source through the inlet valve, the method being in phase with the cycle of the working chamber volume to reduce pressure ripple. Includes closing and opening. In this case, the working fluid can enter the high pressure manifold (from the high pressure working fluid source) at least occasionally through the inlet valve, and the supply of this working fluid is temporarily closed during the active cycle of the working chamber volume. Thus, the additional flow rate of the working fluid compensates for a shortage or deletion in the supply of the working fluid during the active cycle of the working fluid and reduces pressure ripple. This ripple reduction mode is used when the displacement of the hydraulic machine is below the threshold, for example, less than 10% or less than 5% of the maximum displacement of the hydraulic fluid by the hydraulic machine per rotation of the rotatable shaft, and / or high pressure. When a peak of pressure in the manifold and / or soliton is detected or predicted (eg, as a result of a pattern of active and inactive cycles of working chamber volume determined by at least one controller in response to a request signal). , And / or when the ratio of active cycle to inactive cycle of working chamber volume can be below the threshold, i.e. 1: 9 or less. The inlet valve may remain closed when the device is not in ripple reduction mode. When the device is in ripple reduction mode, the inlet valve is open by default and may be closed and reopened once per active cycle of working chamber volume.

The timing of opening and / or closing of the outlet (and / or inlet) valve is in phase relation with the cycle of the working chamber volume: (a) the required signal, (b) the hydraulic machinery (per rotation of the rotatable shaft). Displacement rate and flow rate, (c) Rotable shaft rotation speed, (d) High pressure manifold compatibility (system pressure fluctuation due to volume of working fluid in high pressure manifold), (e) For example, at least one controller , Feedback, feed forward, and / or whether to adjust the displacement in response to the request signal in the open loop control mode, the operating mode of the hydraulic system, (f) the temperature of the working fluid, one or more measurements. Or respond to the calculated value.

If desired, under at least some circumstances, the valve of the electronically controllable working chamber can bring the working fluid to the hydraulic machine at one of several individual maximum displacements, or the active or working chamber volume. It can be controlled to displace in one of a plurality of predetermined patterns of working chambers performing inactive cycles.
The electronically controllable work chamber valve either causes the work chamber to displace one of several individual maximum displacement rates beyond the displacement required to meet the requirements indicated by the received request signal. Controlled to perform one of a plurality of predetermined patterns resulting in a combined displacement of one or more working chambers beyond the displacement required to meet the requirement.
One or more outlet valves are controlled to drain the hydraulic fluid from the high pressure manifold so that the overall displacement of the working fluid into the high pressure manifold meets the requirements.
In some embodiments of the method, electronically controllable working chamber valves are required.
i) If the requirement is met by simply using one or more additional outlets closed and ii) the working fluid displaced by one or more working chambers, active or inactive to meet the requirement. In response to the determination that there is an undesired response (eg, resonance) resulting from the pattern of selection of the working chamber to perform the cycle, the hydraulic machine exceeds the flow required to meet the requirements indicated by the request signal. Can be controlled to displace the working fluid and open one or more outlet valves.

When the requirement falls below the threshold, the electronically controllable work chamber valve causes only a predetermined number of work chambers to perform the active cycle and the other work chamber of one or more work chambers to perform the inactive cycle. May be controlled as Below the threshold, only working chambers that are out of phase by a predetermined amount may perform active cycles and the rest may perform inactive cycles. The predetermined quantity can be 360 ° / n, where n is an integer, in particular 120 ° or 120 ° / n, where n is an integer, which is relatively This is to provide a low ripple output flow rate.

In at least some situations, for example, when a requirement is below a threshold, or for any requirement, an electronically controllable working chamber valve will allow the hydraulic machine to exceed the flow required to meet the requirement, at least. It may be controlled to displace the working fluid, which is a predetermined margin.

Usually, the method further comprises measuring or calculating the current of the flow rate of the working fluid through one or more additional outlets, optionally including measuring the pressure in the high pressure manifold.

The electronically controllable outlet valve also allows, for example, bleeding from the high pressure manifold while the machine is filled with working fluid, to avoid overheating, eg, hot working fluid from the crankcase. Temporarily released to drain, or to warm the working fluid (which can be oil), eg, in the early stages after startup and before normal operation. obtain.

Any feature of any one or more embodiments of any aspect of the invention may be combined with any other feature of any other one or more embodiments of any other aspect of the invention. It will be understood that they can be used together.

An exemplary embodiment of the present invention will be described with reference to the following figures.

It is a schematic diagram of an electronic rectification type machine. 2A-2E are a series of plots showing the response of the electronic rectifying machine according to the present invention. FIG. 5 is a schematic hydraulic view of an electronically controllable outlet valve applied to a hydraulic machine according to an exemplary embodiment of the present invention. It is a flowchart of the procedure for carrying out this invention. It is a series of plots showing the relationship between vehicle speed and flow rate in various embodiments. It is a series of plots showing the relationship between vehicle speed and flow rate in various embodiments. It is a series of plots showing the relationship between vehicle speed and flow rate in various embodiments. It is a series of plots showing the relationship between vehicle speed and flow rate in various embodiments. It is a series of plots showing the relationship between vehicle speed and flow rate in various embodiments. It is a plot of the required flow rate, pump flow, outlet valve flow (upper y-axis), and outlet valve control signal current (lower y-axis) for time (x-axis). It is a plot of pressure fluctuation as a function of time without pressure ripple suppression. It is a plot of pressure fluctuation as a function of time in the ripple reduction operation mode. It is the schematic of the electronic control machine further provided with an inlet valve.

First Example FIG. 1 is a schematic representation of an electronic rectifying machine (ECM) 10, comprising a plurality of working chambers in the form of a cylinder 12, which has an working volume 14 defined by an inner surface of the cylinder. A piston 16 is provided which is driven from a shaft 18 rotatable by an eccentric cam 20 and reciprocates in a cylinder to periodically change the operating volume of the cylinder 12. The rotatable shaft 18 is driven by a prime mover (not shown). The shaft position and speed sensor 22 determines the immediate angular position and rotational speed of the rotatable shaft 18 and notifies the mechanical controller 26 through the signal line 24, whereby the ECM controller 26 immediately cycles each cylinder 12. To determine the phase of. The ECM controller 26 is typically a microprocessor or microcontroller (or a plurality of microprocessors or microcontrollers that can be distributed) that executes a program stored in use.

Each working chamber is associated with a low pressure valve (LPV) in the form of an electronically actuated surface-sealed poppet valve 28, the low pressure valve having an associated working chamber, from the working chamber to the low pressure hydraulic fluid manifold (LPM). ) 30 can be operated to selectively seal the channels extending to 30 and one or more working chambers, or in fact all shown herein, may be connected to the LPM 30 of the ECM 10. The LPV 28 is usually an open solenoid actuated valve, and when the pressure applied from the working chamber onto the poppet is less than or equal to the pressure applied from within the LPM 30 onto the poppet plus the spring force of the LPV spring, that is, intake. During the process, it is passively opened to allow the working chamber to fluidly communicate with the LPM30, but selectively closes under active control of the ECM controller 26 via the LPV control line 34 so as not to fluidly communicate the working chamber with the LPM30. It is possible. Alternatively, the valve may usually be a closed valve.

Each working chamber is further associated with a respective high pressure valve (HPV) 36 in the form of a pressure actuated delivery valve. The HPV 36 can operate to open outward from each working chamber and seal each channel extending from each working chamber to the high pressure hydraulic fluid manifold (HPM) 40, one or more working chambers. Or, in fact, everything shown here can be connected to port 46 in the HPM40. In a similar fashion, the LPV can operate to seal each channel, extending from the working chamber to the low pressure hydraulic fluid manifold (LPM) 30, one or more working chambers, or actually here. All shown can be connected to port 44 in HPM30. The HPV 36 functions as a normally closed pressure release check valve that passively opens when the pressure in the working chamber exceeds the pressure in the HPM 40. The same HPV 36 can be a solenoid operated check valve, which, once the HPV 36 is released by the pressure in the associated working chamber, the mechanical controller 26 is selectively opened via the HPV control line 42. Can be up to. Solenoid actuation can be used to open or close the HPV 36, or to hold it open or closed, depending on its configuration.

In addition to determining, on a cycle-by-cycle basis, whether to close or leave the LPV28 or HPV36 open, the mechanical controller 26 details the closing of the LPV28 and HPV36 with respect to varying the working chamber volume. It can be operated to change the timing (for example, to match the phase). The arrows indicate the hydraulic fluid flow in pumping mode and the flow is reversed in motoring mode. The pressure relief valve 48 can protect the flood control machine from overpressure damage. The fluid in HPM40 drives the motor 56 (an example of an actuator) and flows back into LPM30 when operating in closed circuit mode (not shown) or in open circuit mode (as shown). , Flows into tank 58.

The ECM 10 also has an electronically controllable outlet valve 47 that can be opened and closed by a mechanical controller or another system controller. When opening the electronically controllable outlet valve, some fluid can exit the HPM 40 other than via the actuator 56. The electronically controllable outlet valve 47 is typically a proportional flow valve, i.e., a valve that can be partially opened and is binary in the sense that it can only be stable when fully open or fully closed. In contrast to the valve that is. Therefore, the mechanical controller 26 not only selects whether to open or close the electronically controllable outlet valve 47, but also how much to open or close the electronically controllable outlet valve 47. be able to.

The inputs to the machine controller 26 are the request signal 60 (which can be the maximum displacement Fd), the speed and position of the shaft as measured by the shaft speed and position sensor 24, and the pressure sensor 52 (pressure sensor signal lines are shown). Includes HPM 40 pressure 54 as measured by (not). In some examples, the pressure 54 of the HPM 40, along with the request signal 60, can be used as a feedback signal as part of the pressure control system, but this is not necessarily the case and those skilled in the art will appreciate other request signals. Will understand that can be used. In addition, the machine controller 26 can read (and / or receive data from) database 50 of unauthorized frequencies (eg, Fd values that result in patterns of cylinder operation that give rise to undesired frequencies). In some cases. The output includes valve control signals through LPV and HPV control lines 34 and 42, as well as control signals (via control line 45) to an electronically controllable outlet valve 47.

In some exemplary embodiments, the ECM 10 may also have one or more vibration sensors (eg, accelerometers), where the mechanical controller 26 receives information from the vibration sensors and is detected by the vibration sensors. It may be able to operate to determine the frequency and amplitude of any vibration. In that case, the machine controller 26 can also normally operate to write the vibration data to the database 50. In some cases, the machine controller 26 can also perform machine learning algorithms that can operate to determine patterns of cylinder operation and / or Fd values that give rise to unwanted vibration frequencies and / or amplitudes. In this case, the machine controller 26 can typically also operate to write the output information from the machine learning algorithm to the database 50.

In FIG. 1, all work chambers are connected to the same HPM40, but in some embodiments, such as the second embodiment below, one or more work chambers (coupled to the same shaft). There are multiple groups, each connected to multiple HPMs (and thus to a source or sink of hydraulic fluid, such as a hydraulic actuator or motor). Each group can be controlled according to the individual request signals of each group. In some embodiments, the assignment of working chambers to a group can be dynamically changed during operation, for example using one or more electronically controllable switching valves.

The advantage of using ECMs is that the fluid flow output of each ECM can be changed, cycle by cycle, in rapid response to changing demands. With proper control of the LPV 28 and HPV 36 in phase with the cycle of the working chamber volume, the mechanical controller 26 can control the net displacement of each chamber (LPM30 to HPM40 and vice versa) in each cycle of the working chamber volume. it can. Each working chamber can undergo an active cycle with a net displacement of the working fluid or an inactive (idle) cycle with no net displacement of the working fluid in a given cycle of working chamber volume. The active cycle is a pumping mode cycle with a net displacement of the working fluid from LPM30 to HPM40, driven by the rotation of the rotatable shaft 18, or the working fluid from HPM40 to LPM30 (driving the rotation of the shaft). It can be a motoring mode cycle with a net displacement. An inactive cycle can be achieved by leaving the valve (usually LPV) open throughout the cycle so that the working chamber remains in communication with the manifold throughout the cycle. The net displacement is determined on a cycle-by-cycle basis as to whether to perform an active cycle or an inactive cycle to comply with the target requirement indicated by the request signal 60. The request signal 60 may be a request regarding the pressure of the hydraulic fluid, the flow rate of the hydraulic fluid, the total displacement of the hydraulic fluid, the output, or the position of the actuator hydraulically linked to the hydraulic fluid.

In the pumping mode cycle, the mechanical controller 26 subsequently by actively closing one or more LPV 28s and closing the path to the LPM 30 near the maximum volume point in the cycle of the associated work chamber. By directing the hydraulic fluid out through the HPV 36 associated with the contraction stroke (but not actively holding the opening of the HPV 36), the net displacement rate of the hydraulic fluid from the working chamber to the HPM 40 by the hydraulic motor 56 is selected. The mechanical controller 26 selects the number and order of LPV closures (and HPV openings) to generate flow or shaft torque or power, whereby the request signal 60 (which is the selected net). The request signal 60 associated with the displacement factor) is met or exceeded.

In motoring mode operation, the hydraulic machine controller 26 is displaced by the hydraulic machine via the HPM 40 by actively closing one or more LPV 28s just prior to the minimum volume point in the associated work chamber cycle. Select the net displacement rate of the hydraulic fluid. This closes the path to the LPM 30, which causes the hydraulic fluid in the working chamber to be compressed by the remaining contraction stroke. The associated HPV 36 is released when the pressures across it are equal and a small amount of hydraulic fluid is directed outward through the associated HPV 36 which remains open by the hydraulic machine controller 26. The mechanical controller 26 then actively holds the openness of the associated HPV 36 up to near the maximum volume in the cycle of the associated working chamber, allowing hydraulic fluid to enter the working chamber from the HPM 40 into a rotatable shaft 18. Apply torque.

During use, the machine controller 26 normally receives the request signal 60 in the form of a displacement factor (Fd) signal and executes an algorithm to determine whether to execute an active cycle. The controller can compare the accumulated actual displacement to the accumulated request and perform an active cycle if the difference between the two exceeds a threshold. Therefore, the net displacement by the group of working chambers connected to the HPM is thereby adjusted to meet this requirement.

However, in some situations, with respect to a particular value of Fd (eg, a value associated with low flow, pulsatile flow, or resonance), the mechanical controller 26 instead requires a net displacement of the working chamber to meet the requirement. It should be greater than the amount, thus avoiding patterns of working chamber operation that can cause excessive pulsation, or resonance. In such a situation, the mechanical controller 26 also opens (eg, at least partially) the electronically controllable outlet valve 47. The volume of fluid moving to the HPM 40 beyond the required amount (during pumping), as indicated by the request signal 60 (ie, excess Fd), is thereby via an electronically controllable outlet valve 47. It can exit and return to the LPM 30 in closed circuit mode, otherwise it may be diverted to tank 58 in open circuit mode. This offers the advantage of avoiding low flow rates and pulsating (and therefore likely to cause resonance) flow rates, thus as well as potential user discomfort, vehicles, machines, or machines. Potential damage to the components is reduced, but the net displacement of the working fluid to the HPM 40 is a requirement after allowing the loss of the working fluid through the outlet valve 47, in this case the requirement to the motor 56. Meet.

2A-2E are a series of plots showing the operation of the electronic rectifying machine 10 according to the present invention. FIG. 2A is a plot of the required flow rate 60 as a function of time, FIG. 2B is a plot of Fd102 as a function of time, and FIG. 2C is the position of the electronically controllable outlet valve 47 as a function of time. A plot of 104, FIG. 2D is a plot of loss 106 as a function of time (ie, flow from HPM through an additional outlet controlled by an electronically controllable outlet valve 47), FIG. 2E. Is a plot of net flow rate 108 as a function of time.

At time t _1, the request signal received by the controller, changes to a new level, in this case, indicating a reduced demand. The controller uses the controller's algorithm to determine whether this requirement is met with the usual pattern of active and inactive cycles (ie, to select active or inactive cycles for each cycle of working chamber volume. Whether or not the requirement is met by having the ECM output a flow rate corresponding to the required flow rate) is determined, and when the outlet valve 47 is closed, this potentially results in pulsatile flow. As a result, the mechanical controller 26 causes the cylinder connected to the HPM 40 to generate a flow that exceeds the reduced required flow rate (provided that the mechanical controller 26 receives the request signal 60 indicating the reduced required flow rate before the total flow rate is received. This can still be a reduction in total flow rate when compared to the output (which is usually the case). A higher percentage of cylinders connected to the HPM go through an active (instead of inactive) cycle than a cycle that occurs separately in response to the request signal 60. At the same time, the electronically controllable outlet valve 47 opens to a controlled partially open position so that a portion of the output flow rate corresponding to the excess flow rate generated can exit through the electronically controllable outlet valve 47. it can. In the open circuit arrangement shown in FIG. 1, excess flow exiting through the electronically controllable outlet valve 47 is directed to the tank 58. Therefore, the net flow rate (the output flow rate from the work chamber minus the excess flow rate from the work chamber) meets the required flow rate, while the pulsating flow from the work chamber is reduced or avoided. When the required flow rate changes to a level that does not cause unwanted resonance or pulsatile flow, the electronically controllable outlet valve 47 is closed and the cylinder performs the required Fd (although the outlet valve 47 always at least partially. It is different from the case shown in FIG. 5D which is opened.
Second Example FIG. 3 is a diagram of a control circuit of a vehicle 200 provided with a hydraulic transmission according to the present invention (in this embodiment, the vehicle is a forklift truck). The vehicle 200 includes a fluid-operated machine 150 and an engine 152 that functions as a prime mover and drives the fluid-operated machine through a rotatable shaft 154. The shaft may be connected directly or indirectly (ie, through a torque connecting member or gear train) to the output shaft of the prime mover. The fluid-operated machine is controlled as a mechanical controller 156 that electronically communicates with the vehicle controller 158, and independent pumps 160, 162, 164 (first, second, third pumps), each of which has its own high pressure manifold. It has three groups of working chambers communicating with 166, 168, and 170 (first, second, third high pressure manifolds). A separate fixed positive displacement pump 172 is also coupled to the rotatable shaft 154. The working chamber communicates with a low pressure manifold 174 extending to tank 176. The fluid actuating machine may be formed in a single housing containing a group of working chambers controlled as independent pumps, or may have multiple housings. The mechanical controller and the vehicle controller function as at least one controller. The third high pressure manifold functions as the high pressure manifold of the present invention.

The first high pressure manifold 166 drives one or more actuators 178 in an open circuit hydraulic arrangement. Actuators are traction motors, lifts, tilts, sidearms, single-acting or double-acting rams, such as stick rams, bucket rams, and / or other hydraulically actuated devices, depending on the type of vehicle 200 and its intended use. May include. A third high pressure manifold 170 is used to drive the wheel motor (s) 180, which in turn includes a directional control valve group 186 with a directional control valve (DCV), a propulsion system manifold (PSM). Each wheel 182 is driven via a block 184, which comprises two bidirectional solenoid actuating directional control valves, providing a high pressure line for the pump simultaneously on one side of the bidirectional motor. A single wheel motor may drive multiple wheels or only one wheel. There may be an intermediate gearbox between the wheel motor and the wheel (s). The connection from the third hydraulic manifold to the directional control valve group functions as actuator port 196. The third high pressure manifold also has an outlet 188 (acting as an additional outlet) through the proportional control valve 190, which acts as an electronically controlled outlet valve, which is powered by a fixed positive displacement pump 172. It is connected to the output line 194 of the static pressure steering unit 192. The output line 194 exceeds the tank pressure so that some potential energy is retained and reused. A hydraulic fluid in a closed circuit is supplied to the wheel motor. The electronically controlled outlet valve is typically connected in series with the check valve to prevent the hydraulic fluid from flowing into the high pressure manifold 170 through the additional outlet. The switching valve 165 switches the second high pressure manifold, thus switching the output of the second pump between the first high pressure manifold 166 and the third high pressure manifold 170, thereby assisting in switchability. Can be done. The engine 152 normally drives the pumps 160, 162, 164, and 172, but in some situations, such as during regenerative braking or when reducing the load to recover gravitational potential energy, the pumps 160, 162, 164. Some or all of the may perform a motoring cycle instead of a pumping cycle while the rotatable shaft continues to rotate in the same direction. Pumps 160, 162, and 164 are usually different groups of working chambers within a single fluid-operated machine with an integrated controller 156, but they may be separate pumps. The fixed positive displacement pump 172 is usually a separate device, but may be formed from a group of working chambers within a fluid-operated machine where only check valves can be used instead of electronically controlled valves.

The vehicle controller 158 communicates electronically with the ECM controller 156 and the electronic switching valve 165. The ECM controller can operate to independently control the working chambers of the individual pumps in response to each received request signal. In the case of the actuator 178, these may be signals regarding the pressure in the first high pressure manifold 166, after one or more switching valves, or signals regarding the position or speed of movement of the actuator. The working chamber of the first pump is controlled according to a known algorithm to carry out each requirement.

With reference to FIG. 4, for the third high pressure manifold, the request signal is received or calculated from the wheel motor requirements. The requirements usually change with the speed of the vehicle, and this signal is used to calculate the displacement factor Fd required for the third pump 164. The required displacement rate depends on the rotational speed of the rotatable shaft, as the actual displacement of the working fluid in terms of volume is proportional to both the displacement rate and the rotational speed of the rotatable shaft. The vehicle controller then asks if this displacement rate can cause problems, that is, the active and inactive cycles of the working chamber that the fluid-operated machine controller performs in response to the displacement rate signal (Fd). Determine if the pattern causes vibration, pulsating flow, etc. If the problem is not predicted 254, then the displacement factor calculated for the third pump is sent directly to the fluid-operated machine controller 156 for implementation. However, if a problem is predicted, instead the vehicle controller calculates a modified displacement factor Fd'that is higher than Fd and selected to mitigate the predicted problem, and also a proportional flow valve. A valve open position for 190 is also calculated, which allows some hydraulic fluid to flow from the third high pressure manifold 170 through the electronically controlled proportional flow valve 190, and then a third to meet the requirement. It will provide a net displacement of the working fluid to the high pressure manifold 170. The vehicle controller then sends the modified displacement factor Fd'to the fluid-operated machine controller 156 and also sends a control signal to the proportional flow valve 190. The fluid-operated machine controller 156 receives the modified request signal Fd'and executes its algorithm to determine whether each cycle should be activated or deactivated to satisfy the received request signal.

In this embodiment, the electronically controllable outlet valve 190 is connected between the third high pressure manifold and the low pressure side of the steering mechanism, from the high pressure manifold to the low pressure manifold or tank, or to a different high pressure manifold. The exit may be adjusted. In this embodiment, the electronically controllable outlet valve 47 is inside the PSM block (184), but may be outside the PSM block.

Thus, in some embodiments, the displacement of the third pump 164 may be limited to a particular tolerance level (eg, via the vehicle controller), eg, only a particular displacement may be allowed. , Or certain displacements may be prohibited. These limited permissible displacements can vary depending on the rotational speed of the rotatable shaft. When the received request is not fulfilled, the higher demand is fulfilled and the electronically controllable outlet valve 190 is properly controlled so that the wheel motor receives the required fluid.

There are many different ways in which the actual displacement of individual pumps and electronically controllable outlet valves 190 can be controlled, and some examples are shown in FIGS. 5A-5E. In these figures, the y-axis represents the flow (volume per second) at vehicle speed (x-axis). The required flow rate is indicated by the dotted line 300, the net flow rate displaced by the pump 164 and, in some cases 162, is indicated by the solid line 302, and the leak flow through the electronically controlled outlet valve 190 is indicated by the dashed line 304. Is done. In these embodiments, the required flow rate is the sum of the net displacement of the pump minus the leak flow.

The various embodiments shown in FIGS. 5A-5E each address the problem of pulsatile flow at low flow rates, and the embodiments of FIGS. 5B, 5C, and 5D are active at undesired secondary frequencies. And address the issue of avoiding the generation of patterns of inactive work chamber operation.

In the exemplary embodiment of FIG. 5A, the vehicle speed, when it is between the threshold value S _A of zero and the vehicle speed, the controller maintains the minimum pump flow rate F _A. In between zero speed and S _A rate request displacement ratio Fd is low, leading to an active cycle of irregularly interspersed between the more frequent inactive cycle, causing pulsating flow and / or resonance. Pulsatile flow (or resonance) in this region or range is avoided by the vehicle controller that maintains the pump flow of FA _, outside the problem area or range, thereby overriding the required displacement factor Fd. To. At the same time, the electronically controllable outlet valve 190 is adjusted to be at least partially open. In the flow F _A, the working chamber to provide a smooth flow, for example, three work chambers mutually 120 ° phase difference is used.

The excess flow rate 304 then exits the manifold 170 via the outlet valve 190. When the vehicle speed increases from 0 to S _A, required flow rate is close to the point X, in this case, be consistent request directly are no longer associated with a pulsating flow and / or resonance, electronically controllable outlet valve 190 The portion of the flow rate exiting the manifold 170 through is reduced to zero. At point X, when the speed above the S _A, calculated requested Fd is performed without modification.

In the embodiment of FIG. 5B, in order to obtain the required flow rate 300, the actual pump flow rate 302 is one of a series of evenly spaced discrete values A, B, C, D, E, depending on the vehicle speed. take. These individual flow values are selected to avoid resonance or other problems associated with unwanted vibration or pulsatile flow. At the bottom of the speed range associated with each individual flow rate, the electronically controllable outlet valve 190 is closed and gradually opened as the speed increases until it is fully opened, and the actual pump flow rate is as follows: Increased to individual levels, the electronically controllable outlet valve is closed again.

In the embodiment of FIG. 5C, at most of the vehicle speed, there is at least some leakage through the outlet valve 190. Pump flow 302, the speed _S A to S _B, and also exceeds the _S C to S _D or _{S E,,} is the same as the required flow rate 300. These are velocities in which this pump flow is not expected to cause unwanted vibration or pulsatile flow. Other speed range which can be expected to give rise to undesirable vibration or pulsating flow, as the flow rate range 1 and 2, shown in FIG from zero flow to a level F _A. These flow range, the speed 0～S _A speed _S B to S _C, and also corresponds to the speed _S D to S _E, the pump flow is a predetermined value (respectively _F A, _{F C} or _{F E)} It has, which is selected to exceed the required flow rate, and the electronically controlled outlet valve is conditioned correspondingly to cause a leak 304 to meet the required flow rate 300. The minimum flow rate F _A is selected to avoid vibration resulting from pulsating flow. From the speed _{S A} to the speed _{S B,} pump flow rate, the _{F A} increases to _{F B,} the outlet valve is closed and then, from the speed _{S B} to _{S c,} flow _{rate, F C.} Is maintained at. In speed S _B, the amount of leakage flow is the maximum F _l2, decreases linearly to 0 throughout this range. Leakage flow is not, the pump flow rate, the speed _{S C} to _{S D,} then also the speed _{S D} to _{S E,} increases linearly with the speed, pump flow rate, the fixed level _{F E,} the maximum leakage flow _{F l1} the association is maintained, leakage flow is reduced from the speed S _D to S _E, is selected to obtain the desired net flow to the high pressure manifold 170.

In the embodiment of FIG. 5D, the leak flow 304 has a minimum baseline value of _FA0 provided by one or more of the outlet valves (s) that are always present throughout the speed range and are at least partially open. Have. After allowing the leakage flow of 304, the net flow rate to the high pressure manifolds 40, 170 always meets the required flow rate 300. Pump was chosen to provide a smooth pump flow, separate separate "step" level _{F A, F B, F C} , F D, it may be operated in any one of such F _E .. The size of each step is equal _{(i.e., F B, F C, F} D, the flow rate associated with such _{F E} is a simple multiple of the flow rate _{F A),} a smooth flow level _{F A} is given When selected for flow rate, therefore, multiples of this flow rate level can also theoretically produce a smooth flow rate. Each speed _{S A, S B, S C} , S D, the _{S E,} only leakage flow _{F A0} is generated. At other velocities, there is an additional leak due to line 304. Leakage 304 increases discontinuously as vehicle speed increases and then smoothly decreases in a serrated pattern. Point "X", only the pump provides a flow rate of acceptable smooth level without undesirable frequencies, corresponds to the minimum flow level F _A.

In the embodiment of FIG. 5E, when the vehicle speed increases from zero velocity to S _A, leakage flow is kept constant at a flow rate F _A. Leakage flow is switched off exceeds the speed S _A, pump flow, when the vehicle speed increases in the range of 0 to S _A, increased to a higher flow rate F _B from the flow F _A. Thus, the pump flow without below the minimum threshold value F _A pulsating flow exists, it can be a net flow increases with vehicle speed. Again, X is corresponding to the minimum flow level F _A, only the pump, without unwanted frequencies, providing a flow rate of acceptable smooth level.

In the above embodiment, the third hydraulic manifold driven by the third pump 164 is adjusted according to the present invention without contribution from the second pump 162. If the electronic switching valve 165 is switched so that the second pump 162 contributes to the flow of hydraulic fluid to the wheel motor propulsion hydraulic circuit, instead of adjusting the displacement of the cylinders that make up only the third pump 164, the first The manifold 168 of the second and the third manifold 170 both form a high pressure manifold (high pressure manifold), and the combined displacement of the cylinders constituting the third pump 164 and the second pump 162 is adjusted. In some embodiments, two or more outlets are provided, each with a separate electronically controlled outlet valve.

The present invention is also operational if the actuator instead supplies fluid to a third pump 164 and, for example, acts as a motor instead during the regeneration process. The additional outlet valve can be opened or closed as needed to control the flow rate to either or both of the pumps 162 and 164. The loss of hydraulic fluid through the additional outlet valve is considered and the calculation of the flow rate consumed by the pump and the calculation of the loss through the additional outlet valve only need to consider the sign / direction of the fluid flow. Is.

In the above embodiment, the present invention is used to control the flow of hydraulic fluid to the wheel motor propulsion hydraulic circuit by adjusting the flow of the third pump 164 and the position of the proportional flow valve 190. However, the invention also provides an additional outlet from the manifold 166 regulated by an additional electronically controlled valve in the same manner, while simultaneously controlling the displacement of the pump 160 and the position of the additional electronically controlled valve. Pump 160 may be used to control the flow rate of hydraulic fluid to one or more actuators 178. The present invention may be useful, for example, to supply a hydraulic fluid to a hydraulic ram in a tilting function of a hydraulic vehicle (eg, a forklift truck).
Third Example In the first and second embodiments, the outlet valves 47, 190 are proportional flow valves that are usually opened and closed, or adjusted relatively slowly. It is typically relatively slow or at least rare when compared to ECM solenoid-operated LPV28 and HPV36, even if it is a digital valve that opens, closes, or transitions between them. Opened or closed. In addition, it is usually controlled asynchronously with the working chamber volume cycle.

In a third embodiment, shown with reference to FIG. 8, the apparatus generally comprises a first outlet valve 47, which is a proportional flow valve controlled as described above, corresponding to FIG. An outlet valve 62 has been added, which is a solenoid actuated valve that regulates the outlet path from the HP manifold to the tank and is digitally operated between open and closed, typically with a transition time in the range of 1-4 ms. Yes, it is controlled in phase with respect to the cycle of working chamber volume through the control line 45 in the same way as the ECM LPV28 and HPV36.

This exits the HP manifold 40 through an outlet valve so that, in part, the net flow rate to the high pressure manifold meets the requirements and partially damps the pressure ripples and / or solitons in the high pressure manifold. It is used to provide a more controlled flow rate of working fluid. Pressure ripple is a serious problem when the maximum displacement rate is low. For example, at a displacement requirement of 5% of the maximum requirement, the ECM typically causes every 20th working chamber in the sequence to perform an active cycle along with an intervening cycle that is an inactive cycle. Therefore, the flow of fluid to the HP manifold is inherently pulsating.

Referring to FIG. 6, when this occurs or is predicted, the mechanical controller 26 changes the control signal to the second outlet valve 62 before the time of peak flow from the individual working chambers to the HP manifold. , The second outlet valve is opened and closed again after the peak flow rate. This has the effect of reducing the peak pressure and thereby dampening the pressure ripple. In addition, there is a loss of working fluid from the HP manifold, which is a function of the time the valve is open and the pressure difference across each valve while the valve is open, which is a requirement. When calculating the net flow rate to the HP manifold to meet, it needs to be summed with any flow out of the HP manifold through the first outlet valve.

FIG. 6 shows the request signal 400, which is constant over the short period of time shown, the flow of working fluid 402 to the high pressure manifold during the active cycle of the working chamber volume, and the opening and closing in response to the rising edge of the signal. It shows a control signal 404 to the valve that closes in response to the edge, as well as a pulse 406 of fluid flowing through the valve for a period of time 408. Those skilled in the art, experimentally or by calculation, will find the exact timing required considering the opening or closing speed of the second outlet valve and the pressure wave from the working chamber at the location of the second outlet valve. The time required to propagate can be determined.

The electronically controllable second outlet valve is opened for the duration of control pulse 404. The longer the pulse length, the more flow will flow through the second outlet valve (thus, this corresponds to increased flow loss and reduced efficiency as more fluid flows into the tank). .. Pulses of shorter duration have correspondingly lower flow loss but increased pressure fluctuations. The pulse start time or phase (relative to the working chamber volume cycle) and pulse width (working chamber volume cycle time or phase) are selected to obtain the desired level of damping and fluid outflow characteristics.

The control signal to the second outlet valve usually takes the form of an electric current directed to the solenoid actuator of the valve. This signal is usually varied by pulse width modulation. The exact moment when the second outlet valve opens and closes is the strength of the spring holding the valve in either the closed or open position (usually a closed valve, or normally an open valve). In), it is affected by factors such as the momentary pressure in the work chamber. More generally, the open time or phase and pulse width (expressed as time or phase) are
(A) Request signal,
(B) Displacement rate or flow rate of hydraulic machinery,
(C) Rotational speed of the rotatable shaft,
(D) Compatibility of high pressure manifolds (fluctuations in system pressure with volume of working fluid in high pressure manifolds),
(E) Whether the operating mode of the hydraulic system, eg, the controller, adjusts the displacement in response to a request signal in feedback, feedforward, and / or open loop control modes.
(F) It will change depending on one or more measured or calculated values of the temperature of the working fluid.

Normally, the pulse is timed to coincide with the peak of the output flow rate, but in some embodiments of the invention, the pulse can be time offset (eg, preceded by the peak of the output flow rate). Or be delayed). This presents options for optimization, as understood by those skilled in the art.

FIG. 7A is a plot of pressure as a function of time in examples to which the present invention has not been applied. As can be seen from this figure, there is a large fluctuation in pressure over time, and the amplitude of pressure changes between pulses. FIG. 7B is a plot of pressure as a function of time when the present invention is applied. As can be seen from this figure, the amplitude of the pressure ripple is reduced from 20 to 25 bar to about 15 bar in this embodiment.

In this example, the second outlet valve 62 is controlled by the mechanical controller 26, but may be controlled by another controller such as the vehicle controller 158, however, the controller that normally produces the outlet valve control signal is working. It is necessary to receive a signal indicating the phase of the cycle of the chamber volume (such as the shaft position) and information about the sequence of active and inactive cycles of the working chamber volume, which is usually generated by the machine controller in response to the request signal. is there. The second outlet valve will more typically be connected to the LP manifold or tank rather than another manifold, as generally shown in FIG.

Outlet valves, typically provided for the purpose of smoothing pressure ripples, have a relatively high flow capacity and are opened and closed only during the active cycle of the working chamber volume. Relatively high flow capacities require significant damping of pressure ripple, and if such valves remain open for a longer period of time, as described with reference to Example 1 and Example 2, The loss will be very large as it may be needed for the purpose of controlling the net requirement. Therefore, as shown in FIG. 1, in addition to the outlet valve for adjusting the net requirement, an outlet valve for smoothing the pressure ripple is usually provided. Nevertheless, a single outlet valve may be used both to regulate the outflow of working fluid to obtain the desired net flow rate to the HP manifold and to dampen pressure ripple.
Fourth Example In a fourth embodiment, shown in FIG. 9, the device according to FIG. 1 has a digital solenoid actuated inlet valve 64 through which the HP manifold 40 is of higher pressure, such as a charging fluid accumulator. Connected to the fluid source 66. The mechanical controller 26 opens the inlet valve during the active cycle of the working chamber volume and closes the inlet valve during at least the peak flow region of the active cycle of the working chamber volume. Therefore, during the time of peak flow to the working chamber, the fluid is received from the higher pressure fluid source 64 to compensate for the shortage or deficiency of the working fluid supply during the active cycle, i.e. during the minimum pressure. , Again reduce the pressure ripple. If the higher pressure fluid source is the accumulator, above the threshold, it may be filled with fluid from the high pressure manifold through a check valve. The line from the accumulator through the inlet valve to the high pressure manifold contains a restrictor to prevent excessive flow.

Claims (17)

It ’s a hydraulic system,
A hydraulic machine comprising a rotatable shaft, a low pressure manifold and a high pressure manifold, and one or more working chambers having a volume that changes cyclically with the rotation of the rotatable shaft, each working chamber having said low pressure. It has both a low pressure valve that regulates the communication between the manifold and the work chamber and a high pressure valve that adjusts the communication between the high pressure manifold and the work chamber, and for each work chamber, the respective said A hydraulic machine, wherein the low pressure valve and at least one of the respective high pressure valves are electronically controllable work chamber valves.
A high pressure manifold extending between one or more of the working chambers, one or more actuator ports and one or more additional outlets.
With one or more hydraulic actuators fluidly connected to the high pressure manifold through the one or more actuator ports and thus hydraulically driven by the hydraulic machine.
With one or more electronically controllable outlet valves that regulate the opening or closing of the one or more additional outlets.
Includes said one or more electronically controllable work chamber valves and at least one controller configured to control said one or more electronically controllable outlet valves.
The at least one controller receives the request signal and adjusts the one or more electronically controllable working chamber valves in phase with respect to the cycle of the working chamber volume, thereby each cycle of the working chamber volume. When it is possible to adjust the net displacement of the working fluid by the working chamber and simultaneously adjust the one or more electronically controllable outlet valves, thereby opening one or more additional outlets. The required, by adjusting the net displacement of the working fluid to or from the high pressure chamber, which allows the flow of the working fluid from the high pressure chamber through the one or more additional outlets. A hydraulic system that meets the requirements indicated by the signal. The at least one controller controls the electronically controllable work chamber valve to cause the hydraulic machine to displace the working fluid beyond the requirement indicated by the request signal and open one or more outlet valves. The net displacement of the working fluid from the one or more working chambers through the high pressure valve into the high pressure manifold is thereby configured from the high pressure manifold through the one or more additional outlets. The hydraulic system according to claim 1, wherein after allowing the flow of the working fluid, the hydraulic system is adjusted to meet the requirements indicated by the request signals. The first or second aspect of claim 1, wherein the one or more outlet valves (s) are variable flow control valves and the at least one controller controls the variable flow control valves over a range of positions. Hydraulic system. Claims 1-3, wherein at least one controller opens and closes the outlet valve in phase with respect to the cycle of working chamber volume to reduce pressure ripple in the high pressure manifold. The hydraulic system according to any one item. The high pressure manifold communicates with a higher pressure working fluid source through the inlet valve, and at least one controller closes the inlet valve in phase with the cycle of the working chamber volume to reduce pressure ripple. The hydraulic system according to any one of claims 1 to 4, which is configured to open and open. One or more of the additional outlets extend from the high pressure manifold to the low pressure manifold so that one or more outlet valves pass through the one or more of the additional outlets from the high pressure manifold to the low pressure manifold. The hydraulic system according to any one of claims 1 to 5, which regulates the flow of working fluid to. One or more of the additional outlets extend from the high pressure manifold to the further manifold so that each of the one or more outlet valves is from the high pressure manifold through the one or more of the additional outlets. The hydraulic system according to any one of claims 1 to 3, which regulates the flow of working fluid to the further manifold. The hydraulic system according to claim 7, wherein the additional manifold is a pressurized manifold in which fluid communicates with one or more actuators. 7. The hydraulic system of claim 7 or 8, wherein the high pressure manifold is part of a closed circuit hydraulic arrangement, the additional manifold is part of an open circuit hydraulic arrangement, and vice versa. The hydraulic system comprises a prime mover coupled to the hydraulic machine to provide the hydraulic machine with power to pump the working fluid from the low pressure manifold to the high pressure manifold, and the hydraulic system pumps the working fluid from the low pressure manifold. Alternatively, it further comprises a second hydraulic machine driven by the prime mover or one or more additional work chambers of the hydraulic machine, which is configured to pump from another low pressure manifold to the additional manifold. The hydraulic system of claim 9, wherein the prime mover powers both open and closed hydraulic arrangements. The hydraulic system according to any one of claims 1 to 10, which is a hydraulic vehicle, for example, a forklift truck. A method of operating a hydraulic system, wherein the hydraulic system
A hydraulic machine comprising a rotatable shaft, a low pressure manifold and a high pressure manifold, and one or more working chambers having a volume that changes cyclically with the rotation of the rotatable shaft, each working chamber having said low pressure. It has a low pressure valve that adjusts the communication between the manifold and the work chamber, and a high pressure valve that adjusts the communication between the high pressure manifold and the work chamber, and for each work chamber, each said low pressure valve. And hydraulic machinery, where at least one of the high pressure valves is an electronically controllable work chamber valve.
A high pressure manifold extending between one or more of the working chambers, one or more actuator ports, and one or more additional outlets.
With one or more hydraulic actuators fluidly connected to the high pressure manifold through one or more actuator ports and thereby driven hydraulically by a hydraulic machine.
It comprises one or more electronically controllable outlet valves that regulate the opening or closing of the one or more additional outlets.
The method adjusts the one or more electronically controllable working chamber valves in phase with respect to the cycle of the working chamber volume in response to receiving the request signal, thereby the working chamber volume. When adjusting the net displacement of the working fluid by each working chamber in each cycle and simultaneously adjusting the one or more electronically controllable outlet valves, thereby opening one or more additional outlets. The net displacement of the working fluid to or from the high pressure chamber, which allows the flow of the working fluid from the high pressure chamber through the one or more additional outlets, is adjusted and indicated by the request signal. How to meet the requirements, including. The electronically controllable work chamber valve is controlled to displace the working fluid beyond the requirement indicated by the request signal to the hydraulic machine, and one or more electronically controllable outlet valves are open. The net displacement of the working fluid from the one or more working chambers to the high pressure manifold is controlled so that the working fluid is from the high pressure manifold through the one or more additional outlets. 12. The method of claim 12, wherein after allowing the outflow, the requirement is adjusted to meet the requirement indicated by the request signal. When the requirement falls below the threshold, the electronically controllable working chamber valve performs an active or inactive cycle of working fluid at a predetermined minimum rate of maximum displacement to the hydraulic machine or of working chamber volume. It is controlled to displace in a predetermined pattern of
13. The thirteenth aspect, wherein the one or more outlet valves are controlled to drain the hydraulic fluid from the high pressure manifold so that the overall displacement of the working fluid into the high pressure manifold meets the requirements. the method of. Under at least some circumstances, the electronically controllable working chamber valve provides the hydraulic fluid with working fluid at one of several individual maximum displacements, or with active or inactive cycles of working chamber volume. One of a plurality of predetermined patterns of the working chamber to be performed, which is controlled to be displaced.
Of a plurality of individual maximum displacement rates, the electronically controllable work chamber valve exceeds the displacement required to meet the requirement indicated by the received request signal in the work chamber. Perform one of the plurality of predetermined patterns that displace one or result in the combined displacement of the one or more working chambers so as to exceed the displacement required to meet the requirement. It is controlled to let
13 or claim that the one or more outlet valves are controlled to drain the hydraulic fluid from the high pressure manifold so that the overall displacement of the working fluid into the high pressure manifold meets the requirements. Item 14. The method according to item 14. The electronically controllable work chamber valve has the above requirements.
i) To meet the requirements if the one or more additional outlets are closed and ii) the requirements are met simply by using the working fluid displaced by the one or more working chambers. In response to the determination that there is an undesired response from the system resulting from the pattern of selection of the working chamber to perform an active or inactive cycle, the hydraulic machine has said the request indicated by the request signal. The method of any one of claims 13-15, wherein the method is controlled to displace the working fluid beyond the flow required to meet and open one or more of the outlet valves. 13. To claim, comprising measuring or calculating the current of the flow rate of the working fluid through one or more of the additional outlets, and optionally including measuring the pressure in the high pressure manifold. The method according to any one of 16.