Patent Description:
A variety of hydraulic machines obtaining power through the supply of pressurized fluid are used in construction sites, industrial sites, and the like. For example, in such a hydraulic machine, a pressurized fluid supply feeds pressurized fluid to respective actuators, and working devices connected to the respective actuators perform work using the pressure and the flow rate of the pressurized fluid. Such a hydraulic machine is designed such that working fluid is supplied to respective actuators at an optimum flow rate.

However, specific working devices, referred to as option working devices, require a variety of flow rates depending on the type thereof. A first type of working device may require a flow rate lower than the capacity of a working fluid supply, a second type of working device may require a flow rate the same as the capacity of a working fluid supply, and a third type of working device may require a flow rate higher than the capacity of a working fluid supply. When an option working device requires a flow rate higher than the capacity of a working fluid supply corresponding thereto, a hydraulic machine provides an option actuator with working fluid at a flow rate obtained by combining flows of working fluid discharged by a plurality of working fluid supplies. In this case, when working fluid is supplied to the option actuator, in particular, a motor, at an excessive flow rate, the option actuator may be damaged. It is therefore necessary to control the supply of working fluid to the option actuator such that the flow rate of working fluid is not higher than the maximum allowable flow rate of the option actuator.

<FIG> is a flowchart schematically illustrating a flow rate control algorithm performed in a hydraulic machine of the related art.

Referring to <FIG> (together with <FIG>), specific hydraulic machines of the related art control working fluid supplies, i.e. a first working fluid supply and a second working fluid supply, such that a maximum flow rate of working fluid discharged thereby is not higher than a maximum flow rate of working fluid allowed to be supplied to an option actuator (hereinafter, referred to as a "first maximum allowable flow rate), to prevent the option working device from being damaged. For example, in the case in which the first maximum allowable flow rate is set to be <NUM> lpm and the maximum flow rate of working fluid dischargeable by the first working fluid supply (hereinafter, referred to as "first capacity") and the maximum flow rate of working fluid dischargeable by the second working fluid supply (hereinafter, referred to as "second capacity") are <NUM> lpm, when a first flow rate that the working fluid supplies are required to discharge in response to the manipulation of a first manipulator is <NUM> lpm, the second working fluid supply is controlled to discharge working fluid at a flow rate of <NUM> lpm, and the first working fluid supply is controlled to discharge working fluid at a flow rate of <NUM> lpm (= <NUM> lpm - <NUM> lpm). The problem of such a system occurs when the first manipulator and a second manipulator are simultaneously manipulated to perform a combined operation. Operating the second working device causes the second flow control valve to move to cut off the second fluid path, thereby preventing confluence. Consequently, working fluid discharged by the second fluid supply cannot reach the first flow control valve. Since the option actuator is only supplied with working fluid discharged by the first working fluid supply, the speed of the option working device is significantly reduced, leading to significantly lowered workability. For example, even in the case in which the option actuator requires working fluid at a flow rate of <NUM> lpm in the above-described example, working fluid may only be supplied at a flow rate of <NUM> lpm by the first working fluid supply, thereby significantly lowering the workability of the option working device. <FIG> is a flowchart schematically illustrating a flow rate control algorithm performed in another hydraulic machine of the related art.

Referring to <FIG> (together with <FIG>), in specific hydraulic machines of the related art, the first working fluid supply is controlled to discharge working fluid at a flow rate equal to or lower than a first maximum allowable flow rate to prevent an option actuator from being damaged. For example, when the first maximum allowable flow rate is set to be <NUM> lpm and the first capacity is set to be <NUM> lpm, the flow rate of working fluid dischargeable by the first working fluid supply is limited to <NUM> lpm, even in the case in which the first manipulator and the third manipulator are simultaneously manipulated for a combined operation. Thus, working fluid may be supplied to the option working device and the third working device at significantly insufficient flow rates, so that the speeds of the option working device and the third working device are reduced, thereby lowering workability, which is problematic.

<CIT> discloses a hydrraulic machine according to the preambles of claims <NUM> and <NUM>.

Accordingly, the present disclosure has been made in consideration of the above-described problems occurring in the related art, and the present disclosure proposes a hydraulic machine that can obtain excellent workability while minimizing damage to an option actuator.

According to an aspect of the present invention, a hydraulic machine includes the features of claim <NUM>:
a first working fluid supply, with a maximum flow rate dischargeable therefrom being equal to a first capacity; a second working fluid supply; a first working fluid path extending from the first working fluid supply; a second working fluid path extending from the second working fluid supply; a confluence path connecting the first working fluid path and the second working fluid path to selectively allow working fluid from the second working fluid path to be combined with working fluid in the first working fluid path; a first flow control valve located on the first working fluid path to be movable from a first position to a second position to direct working fluid from the first working fluid path to a first actuator; a second flow control valve located on the second working fluid path to be movable from a first position to a second position to direct working fluid from the second working fluid path to a second actuator; a first manipulator generating a first signal to adjust a displacement of the first flow control valve; a second manipulator generating a second signal to adjust a displacement of the second flow control valve; and a controller. The first actuator includes an option actuator, with a maximum flow rate allowed to be supplied thereto being preset to be a first maximum allowable flow rate. The controller controls the first working fluid supply and the second working fluid supply such that the first working fluid supply discharges working fluid at a flow rate equal to the first capacity and the second working fluid supply discharges working fluid at a flow rate obtained by deducing the first capacity from the first maximum allowable flow rate when the first maximum allowable flow rate is higher than the first capacity, a value of the first signal is a maximum level, and a value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level.

According to another aspect of the present invention, a hydraulic machine includes the features of claim <NUM>:
a first working fluid supply, with a maximum flow rate dischargeable therefrom being equal to a first capacity; a second working fluid supply, with a maximum flow rate dischargeable therefrom being equal to a second capacity; a first working fluid path extending from the first working fluid supply; a second working fluid path extending from the second working fluid supply; a confluence path connecting the first working fluid path and the second working fluid path to selectively allow working fluid from the second working fluid path to be combined with working fluid in the first working fluid path; a first flow control valve located on the first working fluid path to be movable from a first position to a second position to direct working fluid from the first working fluid path to a first actuator; a second flow control valve located on the second working fluid path to be movable from a first position to a second position to direct working fluid from the second working fluid path to a second actuator; a first manipulator generating a first signal to adjust a displacement of the first flow control valve; a second manipulator generating a second signal to adjust a displacement of the second flow control valve; and a controller. The first actuator includes an option actuator, with a maximum flow rate allowed to be supplied thereto being preset to be a first maximum allowable flow rate. The controller calculates a first required flow rate as a function of the first maximum allowable flow rate and a value of the first signal, calculates a second required flow rate as a function of a value of the second signal, and controls the first working fluid supply and the second working fluid supply such that the first working fluid supply discharges working fluid at a flow rate equal to the first capacity and the second working fluid supply discharges working fluid at a flow rate obtained by deducing the first capacity from the first maximum allowable flow rate, added to the second required flow rate, when the first maximum allowable flow rate is higher than the first capacity, the value of the first signal is a maximum level, and the value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level.

Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Hydraulic machines presented in the present disclosure may be machines used in a variety of fields to perform work using hydraulic pressure. For example, hydraulic machines presented in the present disclosure may be construction machines, industrial machines, or the like. In particular, hydraulic machines presented in the present disclosure may be employed in construction machines, such as excavators.

<FIG> is a flowchart schematically illustrating a flow rate control algorithm performed in a hydraulic machine according to exemplary embodiments.

Referring to <FIG> together with <FIG>, a hydraulic machine includes a first working fluid supply <NUM>, a second working fluid supply <NUM>, a first actuator <NUM>, and a second actuator <NUM>. The hydraulic machine includes a first flow control valve <NUM>, a second flow control valve <NUM>, a first manipulator <NUM>, a second manipulator <NUM>, and a controller <NUM>. The hydraulic machine includes a first working fluid path <NUM> and a second working fluid path <NUM>. The hydraulic machine includes a confluence path <NUM>.

The hydraulic machine may include a bypass cutoff valve <NUM>. Although the bypass cutoff valve <NUM> may include a spool, as as illustrated in <FIG>, the bypass cutoff valve <NUM> may include a poppet. In addition, although any valve other than the bypass cutoff valve <NUM> is described and illustrated as including a spool in the specification and the drawings, it should be understood that this is merely illustrative. For example, although the first and second flow control valves <NUM> and <NUM> are illustrated as including spools, respectively, it is to be understood that poppets may be provided in place of the spools. In addition, although the drawings illustrate embodiments in which respective valves (or sub-valves) are integrated into the first flow control valve <NUM> (the first working fluid supply <NUM> -> a valve opening and closing a flow of working fluid to one side of the first actuator <NUM>, the other side of the first actuator <NUM> -> a valve opening and closing a flow of working fluid to a tank <NUM>, the first working fluid supply <NUM> -> a valve opening and closing a flow of working fluid to the other side of the first actuator <NUM>, and one side of the first actuator <NUM> -> a valve opening and closing a flow of working fluid to the tank <NUM>), it should also be understood that these embodiments are merely illustrative. For example, these valves (or sub-valves) may be disposed independently of each other (independent metering valves). The hydraulic machine may include a control valve <NUM>. The hydraulic machine may include a first input device <NUM>. The hydraulic machine may include a prime mover <NUM> and regulators <NUM> and <NUM>. The hydraulic machine may include a first pressure sensor <NUM> and a second pressure sensor <NUM>. The hydraulic machine may include the tank <NUM>.

The first working fluid supply <NUM> may send fluid from the tank <NUM> to the first actuator <NUM>. The first working fluid supply <NUM> may be a hydraulic pump.

The second working fluid supply <NUM> may send fluid from the tank <NUM> to the second actuator <NUM>. The second working fluid supply <NUM> may be a hydraulic pump.

The first actuator <NUM> comprises an option actuator driving an option working device (e.g. a hammer, a crusher, or the like). A maximum flow rate of working fluid allowed to be supplied to the first actuator <NUM> (i.e. a first maximum allowable flow rate) is preset. In this regard, the hydraulic machine may include the first input device <NUM> with which an operator sets the first maximum allowable flow rate. Additionally or alternatively, the hydraulic machine may automatically detect an option working device and automatically set a first maximum allowable flow rate corresponding to the detected option working device.

The second actuator <NUM> may be an actuator driving a working device, for example, a boom, an arm, a bucket, or the like.

The first working fluid path <NUM> extends from the first working fluid supply <NUM>. Working fluid discharged by the first working fluid supply <NUM> is sent to the first flow control valve <NUM> along the first working fluid path <NUM>.

The second working fluid path <NUM> extends from the second working fluid supply <NUM>. Working fluid discharged by the second working fluid supply <NUM> is sent to the second flow control valve <NUM> along the second working fluid path <NUM>.

The confluence path <NUM> connects the first working fluid path <NUM> and the second working fluid path <NUM>. The confluence path <NUM> selectively allows working fluid flowing through the second working fluid path <NUM> to be combined with working fluid flowing through the first working fluid path <NUM>. For the hydraulic machine to allow such a combined flow of fluid, i.e. a confluence, the first maximum allowable flow rate is required to be higher than a maximum flow rate of working fluid that the first working fluid supply <NUM> can supply (i.e. a first capacity). The confluence path <NUM> may be connected to the second working fluid path <NUM>, in a location upstream of the bypass cutoff valve <NUM> as will be described later. The confluence path <NUM> may be connected to (a path parallel to) the first working fluid path <NUM>, in a location upstream of the first flow control valve <NUM>. As illustrated in <FIG>, a check valve may be located on the confluence path <NUM>.

The first flow control valve <NUM> is located on the first working fluid path <NUM>. The first flow control valve <NUM> has a first position and a second position. The first position may be a neutral position, while the second position may be a non-neutral position. The first flow control valve <NUM> is movable from the first position, the neutral position, to the second position, the non-neutral position, in response to, for example, working pressure being applied thereto. When the first flow control valve <NUM> is in the neutral position, working fluid flowing from the first working fluid supply <NUM> may return to the tank <NUM> instead of being supplied to the option actuator <NUM>. The second position may include a third position and a fourth position. The direction in which working fluid flows between the option actuator <NUM> and the first flow control valve <NUM> when the first flow control valve <NUM> is in the third position may be opposite to the direction in which working fluid flows between the option actuator <NUM> and the first flow control valve <NUM> when the first flow control valve <NUM> is in the fourth position.

The second flow control valve <NUM> is located on the second working fluid path <NUM>. Likewise, the second flow control valve <NUM> includes a first position and a second position. The first position may be a neutral position, while the second position may be a non-neutral position. The second flow control valve <NUM> is movable from the first position, the neutral position, to the second position, the non-neutral position, in response to, for example, a working pressure being applied thereto. When the second flow control valve <NUM> is in the neutral position, working fluid flowing from the second working fluid supply <NUM> may return to the tank <NUM> instead of being supplied to the second actuator <NUM>. The second position may include a third position and a fourth position. The direction in which working fluid flows between the second actuator <NUM> and the second flow control valve <NUM> when the second flow control valve <NUM> is in the third position may be opposite to the direction in which working fluid flows between the second actuator <NUM> and the second flow control valve <NUM> when the second flow control valve <NUM> is in the fourth position.

The first manipulator <NUM> generates a first signal to adjust a displacement of the first flow control valve <NUM>.

The second manipulator <NUM> generates a second signal to adjust a displacement of the second flow control valve <NUM>. As illustrated in <FIG>, the second signal may be a hydraulic signal. The second manipulator <NUM> may include a manipulation portion, such as a lever or a pedal, and a pressure-reducing valve (not shown). In response to the manipulation portion being manipulated, the pressure-reducing valve may be moved and may generate a hydraulic signal depending on the displacement of the pressure-reducing valve. The hydraulic signal may be applied to the second flow control valve <NUM> to move the second flow control valve <NUM>. Alternatively, the second signal may be an electrical signal. The second manipulator <NUM> may include a manipulation portion, such as a lever, a pedal, or a wheel, and an electrical signal generator (not shown). The electrical signal generator may generate an electrical signal in response to the manipulation portion being manipulated. The electrical signal may be transmitted to the controller <NUM>, which in turn may transmit a corresponding electrical signal to an electro-proportional pressure-reducing valve (not shown), such that the electro-proportional pressure-reducing valve applies a corresponding pilot pressure to the second flow control valve <NUM>.

The controller <NUM> may include an electronic control unit (ECU). The ECU may include a central processing unit (CPU), a memory, and the like. The controller <NUM> may calculate a first required flow rate as a function of the first maximum allowable flow rate and a value of the first signal and a second required flow rate as a function of the second signal. As discussed above, the first maximum allowable flow rate is variable, changing depending on settings, and the first required flow rate is a function of both the value of the first signal and the first maximum allowable flow rate. In contrast, a maximum flow rate allowed to be supplied to the second actuator <NUM> may be a constant, and the second required flow rate may be a function only related to a value of the second signal.

The hydraulic machine may include the bypass cutoff valve <NUM>. The bypass cutoff valve <NUM> may be located on the second working fluid path <NUM>, downstream of a location in which the second flow control valve <NUM> is located and a location in which the confluence path <NUM> is connected, to open and cut off the second working fluid path <NUM>. To allow confluence, the bypass cutoff valve <NUM> may cut off at least a portion of the second working fluid path <NUM>. When at least a portion of the bypass cutoff valve <NUM> is cut off, at least a portion of working fluid flowing through the second working fluid path <NUM> after having passed through the second flow control valve <NUM> may flow to the first flow control valve <NUM> through the confluence path <NUM> instead of continuing to flow to the tank <NUM>. The bypass cutoff valve <NUM> may adjust a degree to which the second working fluid path <NUM> is cut off, as a function of the value of the first signal.

The control valve <NUM> may be connected to the bypass cutoff valve <NUM> and operate the bypass cutoff valve <NUM> by applying a pilot pressure to the bypass cutoff valve <NUM>. The controller <NUM> may close the control valve <NUM> when the first maximum allowable flow rate is equal to or less than the maximum flow rate of working fluid that the first working fluid supply may discharge (i.e. a first capacity). (Hereinafter, closing the control valve <NUM> means moving the control valve <NUM> to a closed position in which a second pilot fluid path <NUM> is closed. ) In contrast, when the first maximum allowable flow rate is higher than the first capacity, the controller <NUM> may open the control valve <NUM>. (Hereinafter, opening the control valve <NUM> means moving the control valve <NUM> to an open position in which a second pilot fluid path <NUM> is opened.

The hydraulic machine may include the prime mover <NUM> and the regulators <NUM> and <NUM>. The prime mover <NUM> may drive the first working fluid supply <NUM> and the second working fluid supply <NUM>. The first working fluid supply <NUM> and the second working fluid supply <NUM> may adjust flow rates of fluid discharged by the first working fluid supply <NUM> and the second working fluid supply <NUM> using the regulators <NUM> and <NUM> that control the capacities of the working fluid supplies. The hydraulic machine may include an electro-proportional pressure-reducing valve (not shown). The controller <NUM> may operate the electro-proportional pressure-reducing valve by applying an electrical signal to the electro-proportional pressure-reducing valve. The electro-proportional pressure-reducing valve may operate the regulators <NUM> and <NUM> by applying an amount pilot pressure, corresponding to the electrical signal, to the regulators <NUM> and <NUM>.

Hereinafter, the flow rate control algorithm will be sequentially described with reference to <FIG>.

First, a user sets a first maximum allowable flow rate using the first input device <NUM> or the hydraulic machine automatically sets the first maximum allowable flow rate by recognizing the option working device.

When a first signal from the first manipulator <NUM> is detected, it is determined whether or not the previously-set first maximum allowable flow rate is higher than a first capacity.

When the first maximum allowable flow rate is not determined to be higher than the first capacity, the bypass cutoff valve <NUM> is opened (or is maintained in an open state), the first working fluid supply <NUM> is controlled to discharge working fluid at a first required flow rate that the first working fluid supply <NUM> is requested from the first manipulator <NUM>, and the second working fluid supply <NUM> is controlled to discharge fluid at a second flow rate that the second working fluid supply <NUM> is requested from the second manipulator <NUM>.

In contrast, when the first maximum allowable flow rate is determined to be higher than the first capacity, the bypass cutoff valve <NUM> may be closed, the first working fluid supply <NUM> may be controlled to discharge fluid at a first flow rate equal to or lower than the first capacity, and the second working fluid supply <NUM> may be controlled to discharge fluid at a second flow rate equal to or lower than a value obtained by deducing the first capacity from the first maximum allowable flow rate.

When the first maximum allowable flow rate is higher than the first capacity, the value of the first signal is a maximum level, and the value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level, the first working fluid supply may be controlled to discharge fluid at a flow rate equal to the first capacity, and the second working fluid supply may be controlled to discharge fluid at a flow rate obtained by deducing the first capacity from the first maximum allowable flow rate.

<FIG> is a graph illustrating an exemplary relationship between a first signal generated by the first manipulator and flow rates of fluid discharged by the first working fluid supply and the second working fluid supply when the first maximum allowable flow rate is higher than the first capacity.

Q1 indicates a flow rate of working fluid discharged by the first working fluid supply in response to the first signal, while Q2 indicates a flow rate of working fluid discharged by the second working fluid supply in response to the first signal. (Q2 differs from a second flow rate of working fluid discharged by the second working fluid supply in response to the first signal and a second signal.

For example, when the first maximum allowable flow rate is <NUM> lpm and the first capacity is <NUM> lpm, manipulating the first manipulator alone (e.g. first signal = a < b) may cause the first working fluid supply <NUM> to discharge working fluid at a flow rate d, lower than the first capacity, and the second working fluid supply <NUM> to discharge working fluid at a flow rate c, lower than a value obtained by deducing the first capacity from the first maximum allowable flow rate (= <NUM> lpm).

For example, when the first maximum allowable flow rate is <NUM> lpm and the first capacity is <NUM> lpm, simultaneously manipulating the first manipulator (e.g. first signal = a) and the second manipulator may cause the first working fluid supply <NUM> to discharge working fluid at the flow rate d, lower than the first capacity, and the second working fluid supply <NUM> to discharge working fluid at a flow rate higher than the flow rate c and equal to or lower than a value obtained by deducing the first capacity from the first maximum allowable flow rate (= <NUM> lpm), depending on a second required flow rate.

For example, when the first maximum allowable flow rate is <NUM> lpm and the first capacity is <NUM> lpm, manipulating the first manipulator to a maximum displacement such that the first required flow rate is substantially the same as the first maximum allowable flow rate (first signal = b) may cause the first working fluid supply <NUM> to discharge working fluid at a flow rate corresponding to the first capacity (= <NUM> lpm), and the second working fluid supply <NUM> to discharge working fluid at a flow rate corresponding to a value obtained by deducing the first capacity from the first maximum allowable flow rate (= <NUM> lpm - <NUM> lpm = <NUM> lpm).

Thus, in the case of a combined operation of the first actuator and the second actuator, the movement of the second flow control valve may cause working fluid having a flow rate of <NUM> lpm to be supplied to the first working fluid supply <NUM>, even in the case in which working fluid having a flow rate of <NUM> lpm, discharged by the second working fluid supply <NUM>, is not supplied to the option actuator <NUM> through the confluence path. This can consequently minimize decreases in the workability of the option working device. The hydraulic machine may include at least one flow control valve (not shown) additionally located on the first working fluid path <NUM>, as well as a manipulator (not shown) and an actuator (not shown), corresponding to the additional flow control valve.

Likewise, the hydraulic machine may include at least one flow control valve (not shown), additionally located on the second working fluid path <NUM>, as well as a manipulator (not shown) and an actuator (not shown), corresponding to the additional flow control valve. Even in the case in which at least one of these manipulators requests at least one of the first working fluid supply <NUM> and the second working fluid supply <NUM> to discharge working fluid at an additional flow rate, independently of the first flow rate and the second flow rate, the controller <NUM> may control the first working fluid supply <NUM> and the second working fluid supply <NUM> such that the first working fluid supply <NUM> discharges working fluid at a flow rate equal to or lower than the first maximum allowable flow rate when the first maximum allowable flow rate is equal to or lower than the first capacity and the first working fluid supply <NUM> and the second working fluid supply <NUM> discharges working fluid at a combined flow rate equal to or lower than the first maximum allowable flow rate when the first maximum allowable flow rate is higher than the first capacity.

<FIG> is a flowchart schematically illustrating a flow rate control algorithm performed in the hydraulic machine according to exemplary embodiments.

Although the embodiments illustrated in <FIG> have a different flow control algorithm from the embodiments illustrated in <FIG>, such algorithms may be embodied using the same or similar device configurations. Thus, descriptions of some features will be omitted when they are identical to those of the embodiments described above with reference to <FIG>.

The control algorithm will be sequentially described with reference to <FIG> together with <FIG>.

First, an operator sets a first maximum allowable flow rate using the first input device <NUM> or the hydraulic machine automatically sets the first maximum allowable flow rate by recognizing an option working device.

When a first signal is detected, i.e. the first manipulator is detected as being manipulated, it is determined whether or not the first maximum allowable flow rate is higher than a first capacity. When the first maximum allowable flow rate is determined not to be higher than the first capacity, the bypass cutoff valve <NUM> may be opened (or be maintained in an open state), and the controller <NUM> may control the first working fluid supply <NUM> to discharge working fluid at a first required flow rate and the second working fluid supply <NUM> to discharge working fluid at a second required flow rate.

In contrast, when the first maximum allowable flow rate is determined to be higher than the first capacity of the first working fluid supply <NUM>, the bypass cutoff valve <NUM> may be closed, and the controller <NUM> may control the first working fluid supply <NUM> to discharge working fluid at a first flow rate equal to or lower than the first capacity and the second working fluid supply <NUM> to discharge working fluid at a second flow rate equal to a lower flow rate between a flow rate obtained by deducing the first flow rate from the first required flow rate, added to the second required flow rate, and a flow rate of a second capacity.

When the first maximum allowable flow rate is higher than the first capacity, the value of the first signal is a maximum level, and the value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level, the first working fluid supply may be controlled to discharge working fluid at a flow rate of the first capacity, while the second working fluid supply may be controlled to discharge working fluid at a flow rate equal to a lower flow rate between a flow rate obtained by deducing the first flow rate from the first maximum allowable flow rate, added to the second required flow rate, and the flow rate of the second capacity.

An exemplary relationship between a flow rate of fluid discharged by the first working fluid supply and a flow rate of fluid discharged by the second working fluid supply in response to a first signal generated by the first manipulator when the first maximum allowable flow rate is higher than the first capacity will be described with reference to <FIG>.

For example, when the first maximum allowable flow rate is <NUM> lpm and the first capacity is <NUM> lpm, manipulating the first manipulator alone (e.g. first signal = a < b) may cause the first working fluid supply <NUM> to discharge working fluid at the flow rate d, lower than the first capacity, and the second working fluid supply <NUM> to discharge working fluid at the flow rate c.

For example, when the first maximum allowable flow rate is <NUM> lpm and the first capacity is <NUM> lpm, simultaneously manipulating the first manipulator (e.g. first signal = a) and the second manipulator may cause the first working fluid supply <NUM> to discharge working fluid at the flow rate d, lower than the first capacity, and the second working fluid supply <NUM> to discharge working fluid at a flow rate obtained by adding the flow rate c and the second required flow rate.

For example, when the first maximum allowable flow rate is <NUM> lpm and the first capacity is <NUM> lpm, manipulating the first manipulator to a maximum displacement such that the first required flow rate is substantially the same as the first maximum allowable flow rate (first signal = b) and simultaneously manipulating the second manipulator may cause the first working fluid supply <NUM> to discharge working fluid at a flow rate equal to the first capacity, i.e. <NUM> lpm, and the second working fluid supply <NUM> to discharge working fluid at a flow rate obtained by deducting the first capacity from the first required flow rate, added to the second required flow rate (= <NUM> lpm - <NUM> lpm + second required flow rate).

Consequently, it is possible to supply working fluid at a flow rate as high as possible, required by the option actuator <NUM> and the second actuator <NUM>, thereby improving workability compared to the embodiments as described above with reference to <FIG>. Configurations of the hydraulic machine according to a variety of embodiments for realizing the algorithms illustrated in <FIG> and <FIG> will be described with reference to <FIG>. Since common features have been discussed above with reference to <FIG>, the following descriptions will be given mainly with regard to characteristic features of the embodiments related to the drawings.

<FIG> is a diagram schematically illustrating a configuration of the hydraulic machine according to exemplary embodiments.

As illustrated in <FIG>, the hydraulic machine may include the first pressure sensor <NUM> and the second pressure sensor <NUM>.

As illustrated in <FIG>, the first manipulator <NUM> may generate a first signal as a hydraulic signal. The first manipulator <NUM> may include a manipulator, such as a lever or a pedal, and a pressure-reducing valve. In response to the manipulator being manipulated, the pressure-reducing valve (not shown) may be moved and may generate a hydraulic signal based on a displacement thereof. The hydraulic signal may be applied to the first flow control valve <NUM> to move the first flow control valve <NUM>. The generated hydraulic signal may be detected by the first pressure sensor <NUM>, which in turn may transmit an electrical signal, corresponding to the hydraulic signal, to the controller <NUM>. The second manipulator <NUM> may also generate a second signal as a hydraulic signal. The generated hydraulic signal may be detected by the second pressure sensor <NUM>, which in turn may transmit an electrical signal, corresponding to the hydraulic signal, to the controller <NUM>.

The hydraulic machine may include a first pilot fluid path <NUM> extending between a pressure-reducing valve of the first manipulator <NUM> and the first flow control valve <NUM>. The hydraulic machine may include a second pilot pressure path <NUM> connecting the first pilot fluid path <NUM> and the bypass cutoff valve <NUM>. Likewise, the hydraulic machine may include a pilot fluid path extending between a pressure-reducing valve of the second manipulator <NUM> and the second flow control valve <NUM>.

As illustrated in <FIG>, the control valve <NUM> may be located on the second pilot fluid path <NUM>. The control valve <NUM> may be a simple solenoid valve opening or closing the second pilot fluid path <NUM> in response to an electrical signal applied thereto. Thus, when the control valve <NUM> is opened, the first signal generated by the first manipulator <NUM> may be applied to the bypass cutoff valve <NUM> through the second pilot fluid path <NUM>.

The confluence path <NUM> may be connected to the second working fluid path <NUM>, in a location downstream of the second flow control valve <NUM>.

As illustrated in <FIG>, the hydraulic machine may include an electro-proportional pressure-reducing valve <NUM> moving the first flow control valve <NUM> by applying an amount of pilot pressure to the first flow control valve <NUM>. The hydraulic machine may include the first pilot fluid path <NUM> extending between the electro-proportional pressure-reducing valve <NUM> and the first flow control valve <NUM>. The hydraulic machine may include the second pilot fluid path <NUM> connecting the first pilot fluid path <NUM> and the bypass cutoff valve <NUM>. The control valve <NUM> may be located on the second pilot fluid path <NUM> to open and cut off the second pilot fluid path <NUM>.

The first manipulator <NUM> may generate a first signal as an electrical signal. The first manipulator <NUM> may include a manipulation portion, such as a lever, a pedal, or a wheel, and an electrical signal generator. The electrical signal generator may generate an electrical signal corresponding to an amount by which the manipulation portion is manipulated. The electrical signal may be transmitted to the controller <NUM>, which in turn may provide a corresponding electrical signal to the electro-proportional pressure-reducing valve <NUM> to operate the electro-proportional pressure-reducing valve <NUM>. The electro-proportional pressure-reducing valve <NUM> may apply a pilot pressure, corresponding to the electrical signal, to the first control valve <NUM>.

As illustrated in <FIG>, the first manipulator <NUM> may generate a first signal as a hydraulic signal. The generated hydraulic signal may be detected by the first pressure sensor <NUM>, which in turn may transmit a corresponding electrical signal to the controller <NUM>. The controller <NUM> may apply the corresponding electrical signal to the control valve <NUM>.

The control valve <NUM> may include an electro-proportional pressure-reducing valve. When the controller <NUM> applies an electrical signal to the control valve <NUM>, the control valve <NUM> may be opened or closed by a degree corresponding to the electrical signal to apply a corresponding level of pilot pressure to the bypass cutoff valve <NUM>.

As illustrated in <FIG>, the first manipulator <NUM> may generate a first signal as an electrical signal. The first manipulator may transmit the generated electrical signal to the controller <NUM>. The controller <NUM> may apply a corresponding electrical signal to the control valve <NUM>.

The confluence path <NUM> may be connected to the second working fluid path <NUM>, in a location upstream of the second flow control valve <NUM>. Although the location of the connection of the confluence path <NUM> is discussed as a modification to the embodiments described with reference to <FIG>, the same may be applied to the embodiments described with reference to <FIG>.

Since the confluence path <NUM> is connected to the second working fluid path <NUM>, in a location downstream of the second flow control valve <NUM>, in the embodiments described with reference to <FIG>, working fluid cannot be supplied to the option actuator <NUM> through the confluence path <NUM> when the second working fluid path <NUM> is cut off in response to the second flow control valve <NUM> being moved. Thus, as illustrated in <FIG>, it is possible to further improve the workability of the option working device by connecting the confluence path <NUM> to the second working fluid path <NUM>, in a location upstream of the second flow control valve <NUM>.

Referring to <FIG> together with <FIG>, the hydraulic machine may include the first working fluid supply <NUM>, the first actuator <NUM>, a third actuator <NUM>, the first flow control valve <NUM>, a third flow control valve <NUM>, the first manipulator <NUM>, a third manipulator <NUM>, and the controller <NUM>.

The first flow control valve <NUM> may control a flow of working fluid directed from the first working fluid supply <NUM> to the first actuator <NUM>.

The third flow control valve <NUM> may control a flow of working fluid directed from the first working fluid supply <NUM> to the third actuator <NUM>.

The first manipulator <NUM> may generate a first signal by which the degree of opening of the first flow control valve <NUM> is adjusted. The third manipulator <NUM> may generate a third signal by which the degree of opening of the third flow control valve <NUM> is adjusted. As illustrated in <FIG>, the third manipulator <NUM> may generate a third signal as a hydraulic signal. As an alternative, the third manipulator <NUM> may generate the third signal as an electrical signal. The generated electrical signal may be transmitted to the controller <NUM>, which in turn may apply a corresponding electrical signal to the electro-proportional pressure-reducing valve (not shown).

The first actuator <NUM> may be an option actuator driving the option working device.

The controller <NUM> may calculate the first required flow rate as a function of the first maximum allowable flow rate and a value of the first signal and calculate a third required flow rate as a function of a value of the third signal. The controller <NUM> may control the first working fluid supply <NUM> to supply working fluid to the first actuator <NUM> at the first required flow rate and working fluid to the third actuator <NUM> at the third required flow rate.

For example, when the first capacity of the first working fluid supply <NUM> is <NUM> lpm and the first maximum allowable flow rate is <NUM> lpm, manipulating the option working device alone may limit the flow rate of working fluid discharged by the first working fluid supply <NUM> to be <NUM> lpm. In the case in which the first manipulator <NUM> and the third manipulator <NUM> are simultaneously manipulated, when the required flow rate of the first actuator <NUM> is <NUM> lpm and the required flow rate of the third actuator <NUM> is <NUM> lpm, the first working fluid supply <NUM> may discharge working fluid at a flow rate of <NUM> lpm so that a flow rate of <NUM> lpm is supplied to the third actuator <NUM> and a flow rate of <NUM> lpm is supplied to the first actuator <NUM>. It is thereby possible to supply working fluid at a significantly higher flow rate than in the related art, thereby obtaining efficient workability.

Referring to <FIG> together with <FIG> and <FIG>, the controller <NUM> may adjust the degree of opening of the first flow control valve <NUM> as a function of a value of a first signal and a gain value. In the case in which the first working fluid supply <NUM> supplies working fluid to the third actuator <NUM> and the first actuator <NUM>, when a load pressure applied to the third actuator <NUM> is higher than a load pressure applied to the first actuator <NUM>, a maximal amount of working fluid discharged by the first working fluid supply <NUM> may be introduced into the first actuator <NUM>. In this case, the flow rate of working fluid supplied to the first actuator <NUM> is higher than the first maximum allowable flow rate, so that the first actuator <NUM> may be damaged. In addition, the third actuator <NUM> may not be supplied with working fluid at a flow rate intended by the operator, so that there may be an adverse effect on the operability of the third actuator <NUM>. To prevent such problems, a value obtained by multiplying a value of a first signal (i.e. a value input into the controller <NUM>) with a gain value K may be sent to the electro-proportional pressure-reducing valve <NUM> as an output value. The gain value may be lower than <NUM>. When the value of the first signal is the same (i.e. the amount by which the manipulation portion is manipulated is the same), an electrical signal, the value of which is lower than the value of the electrical signal discussed in the foregoing embodiments with reference to <FIG>, may be applied to the electro-proportional pressure-reducing valve <NUM>, which in turn may apply pilot pressure Pi' to the first flow control valve <NUM>, the pilot pressure Pi' being lower than the pilot pressure Pi discussed in the foregoing embodiments with reference to <FIG>. Thus, the degree of opening of the first flow control valve <NUM> may be reduced, thereby reducing the amount of working fluid supplied to the first actuator <NUM> while increasing the amount of working fluid supplied to the third actuator <NUM>. It is therefore possible to suitably distribute flow rates of working fluid to the third actuator <NUM> and the first actuator <NUM>, thereby controlling the flow rate of working fluid directed to the first actuator <NUM>.

<FIG> is a graph illustrating an exemplary relationship between a third signal of the third manipulator and a gain value.

The controller may calculate a gain value as a function of a value of a third signal and send a value obtained by multiplying a value of a first signal with the calculated gain value, as described above, to the electro-proportional pressure-reducing valve. As described above, the higher the value of the third signal is, i.e. the higher the degree of opening of the third flow control valve is, the lower the gain value may be. Consequently, the higher value of the third signal can further reduce the value of the first signal, i.e. the degree of opening of the first flow control valve, than the lower value of the third signal.

Configurations of the hydraulic machines according to a variety of embodiments for realizing the algorithms illustrated in <FIG> and <FIG> will be described with reference to <FIG>. Since common features have been discussed above, the following descriptions will be given mainly with regard to characteristic features of the embodiments related to the drawings.

As illustrated in <FIG>, the first manipulator <NUM> may generate a first signal as a hydraulic signal. The first pressure sensor <NUM> may detect the first signal and transmit an electrical signal, corresponding to the first signal, to the controller <NUM>.

As illustrated in <FIG>, the hydraulic machine may further include a third pilot fluid path <NUM> connecting the first manipulator <NUM> and the first flow control valve <NUM> and an electro-proportional pressure-reducing valve <NUM> located on the third pilot fluid path <NUM>. The controller <NUM> may control the electro-proportional pressure-reducing valve <NUM> such that the degree of opening of the first flow control valve <NUM> is adjusted depending on a function of a value of a first signal and a gain value.

The hydraulic machine may include a second input device <NUM> with which a gain value of a current output to the electro-proportional pressure-reducing valve <NUM> with respect to the value of the first signal is set.

As illustrated in <FIG>, the hydraulic machine may include the electro-proportional pressure-reducing valve <NUM> connected to the first flow control valve <NUM> to operate the first flow control valve <NUM>. The first manipulator <NUM> may generate a first signal as an electrical signal and provide the first signal to the controller <NUM>. The controller <NUM> may operate the electro-proportional pressure-reducing valve <NUM> by applying an electrical signal, corresponding to the first signal, to the electro-proportional pressure-reducing valve <NUM>.

Claim 1:
A hydraulic machine comprising:
a first working fluid supply (<NUM>), with a maximum flow rate dischargeable therefrom being equal to a first capacity;
a second working fluid supply (<NUM>);
a first working fluid path (<NUM>) extending from the first working fluid supply;
a second working fluid path (<NUM>) extending from the second working fluid supply;
a confluence path (<NUM>) connecting the first working fluid path and the second working fluid path to selectively allow working fluid from the second working fluid path to be combined with working fluid in the first working fluid path;
a first flow control valve (<NUM>) located on the first working fluid path to be movable from a first position to a second position to direct working fluid from the first working fluid path to a first actuator (<NUM>);
a second flow control valve (<NUM>) located on the second working fluid path to be movable from a first position to a second position to direct working fluid from the second working fluid path to a second actuator (<NUM>);
a first manipulator (<NUM>) generating a first signal to adjust a displacement of the first flow control valve;
a second manipulator (<NUM>) generating a second signal to adjust a displacement of the second flow control valve; and
a controller (<NUM>),
wherein the first actuator comprises an option actuator, with a maximum flow rate allowed to be supplied thereto being preset to be a first maximum allowable flow rate, and
characterised in that
the controller controls the first working fluid supply and the second working fluid supply such that the first working fluid supply discharges working fluid at a flow rate equal to the first capacity and the second working fluid supply discharges working fluid at a flow rate obtained by deducting the first capacity from the first maximum allowable flow rate when the first maximum allowable flow rate is higher than the first capacity, a value of the first signal is a maximum level, and a value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level.