Variable displacement hydraulic pump

Abstract

A control system and control method for a variable displacement hydraulic pump, wherein the system includes a detection sensor for detecting an actual set displacement and a control unit for current control of a pair of solenoids for increasing and decreasing the control displacement.

Description

Technical Field

[0001] This invention relates to a variable displacement hydraulic pump. Background Technology

[0002] In the field of variable displacement hydraulic pumps, the use of control systems is known, which allow for changes in the displacement of the variable displacement pump and also allow for reversal of the rotation direction of the actuation system controlled by the pump itself.

[0003] Existing solutions provide pump control via an electro-hydraulic control unit commonly referred to as "RE" (an abbreviation for "Remote Electrical"). A known type of control unit (RE) consists of a set of three solenoids, each driving one of three slide valves. This type of instruction allows manufacturers of vehicles equipped with pumps (such as concrete mixers) to connect the pump directly to a remote control button panel, which allows the operator to control and instruct the pump, and thus the machine, to perform its intended functions.

[0004] Application D1 JPH08177745 describes a solution for improving the accuracy and reliability of a control device for hydraulic pump flow rate. A mechanical flow detection mechanism is provided in the delivery pipe of the hydraulic pump. A feedback spring is also disposed between the outlet element and the coil of a proportional four-way solenoid valve. The delivery flow rate of the hydraulic pump is mechanically relayed to the proportional solenoid valve. A control current corresponding to the desired value of the pump's delivery flow rate is output from the control unit to the solenoid of the proportional solenoid valve.

[0005] Application D2 US7975599 describes a regulating device for a hydrostatic piston engine. The regulating device includes an electronic control unit for generating a regulating signal. The adjusted position of the hydrostatic piston motor, scanned by a feedback element, is detected by a sensor in the non-contact electronic control unit.

[0006] Application D3 EP0087773 describes a control system for a variable displacement pump, comprising a variable displacement pump having a movable element for controlling the pump's displacement, a hydraulic motor for moving the movable element, and a transducer for generating an electrical signal corresponding to the actual position of the movable element. A comparator compares the electrical signal from the transducer with an electrical signal corresponding to the desired pump displacement and generates an error signal. A control unit operates in response to the error signal to measure the fluid flow rate from the pump outlet to the hydraulic motor. The control unit includes a release valve, a compensation valve, and a servo valve. The servo valve is preferably a single-stage valve that includes a damping orifice to provide stability.

[0007] Application D4 US5758499 describes a hydraulic control system suitable for hydraulically addressing problems arising when a control unit controls the displacement of a hydraulic pump based on changes in the state of a hydraulically driven system. To this end, a pump regulator is manufactured that increases the swashplate tilt angle by reducing the pressure of a second hydraulic signal. The pump regulator is configured such that it can be driven using a negative control pressure instead of the second hydraulic signal. Furthermore, the characteristics of the fixed throttle valve and spring in the pump regulator are configured such that the pump regulator can operate within the operating range of the negative control pressure. The control unit sets the corrected negative control pressure as the target value of the second hydraulic signal and determines the second electrical signal corresponding to the target value in a suitable block such that the operating range of the second hydraulic signal generated by the proportional solenoid valve is substantially the same as the operating range of the negative control pressure.

[0008] Application D5 US5205201 describes a displacement control valve with a valve body having a fluid-measuring spool that is axially movable between pilot pressure chambers formed at opposite ends of an inner bore in the valve body. An internal spring feedback device is mounted on the spool in one of the pilot pressure chambers and resiliently connects a swashplate of a variable displacement hydraulic unit to the spool. An elongated housing surrounds the spring and spring guide and is mechanically connected to the swashplate. The housing and spring guide form a fluid seal between the spool and the valve body to seal the pilot pressure chamber of the mounted feedback device.

[0009] Application D6 US2014 / 311139 describes a variable flow hydrostatic pump whose displacement is set by an electro-hydraulic control device equipped with safety functions. In the event of a failure, the variable flow pump is set to an intermediate position. The electro-hydraulic control device has a single electro-hydraulic setpoint encoder for specifying the setpoint value of the variable flow pump's motion, and an electrically actuated valve connected in series downstream of the setpoint encoder to control the direction of motion of the variable flow pump.

[0010] Problems with existing technology

[0011] The known type of RE control group, consisting of a set of three solenoids, has significant drawbacks.

[0012] In the known system, the RE control group is highly dependent on oil temperature, which in turn depends on ambient temperature. This makes the commands of the known system non-repeatable and further raises issues related to the pump's zeroing phase, where additional components are needed to ensure the restoration of the neutral conditions the pump had when it was stopped.

[0013] Hydraulic structures are complex, requiring a large number of components, and there are issues related to the high cost of pumps and their reliability.

[0014] Furthermore, existing systems are irreversible, and the operator gradually increases and decreases the displacement without truly knowing the actual set displacement, as it is obtained through pulse commands applied to the actuating solenoid, whose behavior is not identical to that of the valve.

[0015] The purpose of this invention

[0016] The purpose of this invention is to provide a variable displacement hydraulic pump with an improved control system.

[0017] The content of this invention

[0018] The present invention provides a control system for a hydraulic pump (19), wherein the hydraulic pump is equipped with a displacement changing device, the system includes a displacement changing control device (21), the displacement changing control device is equipped with a servo control device, the cylinder (45) and piston (18) of the servo control device have a connecting device connected to the displacement changing device of the hydraulic pump (19), the cylinder (45) includes a first half and a second half separated by the piston (18), for conveying pressurized fluid, causing the piston (18) to move in a first direction of motion and a second direction of motion opposite to the first direction of motion, respectively, the system includes a control unit, a drive valve (1) and a first control unit for controlling the valve (1). The control unit includes a solenoid (9) and a second solenoid (10), the control unit comprising a displacement increase input and a displacement decrease input, a first output connected to the first solenoid (9) and a second output connected to the second solenoid (10), wherein the valve (1) includes a body (2) provided with conduits for alternately delivering fluid in a first or second half of the cylinder (45), the conduits including an inlet conduit (27), a first control conduit (29) and a second control conduit (28), the valve (1) including a valve core (4) movable within a valve seat (3) between at least three positions: a neutral position for preventing fluid from flowing to the cylinder (45), a position for delivering fluid to the... The system includes a first position of the first half of the cylinder (45) and a second position for conveying fluid to the second half of the cylinder (45), the valve core (4) being connected to an elastic element (37) for returning to a neutral position, the first solenoid (9) and the second solenoid (10) being current-operated solenoids, the system including a position detection device (39) of the servo control device for actual position feedback of the servo control device, the control unit including logic for current control of the first output and the second output based on the feedback of the position detection device (39), characterized in that the position detection device (39) of the servo control device includes a pin (47) which is connected to a lever (4) 8) Connected to the servo control device such that the movement of the pin (47) corresponds to the movement of the servo control device, an elastic element (37) for returning to the neutral position is disposed between a pair of arms (41, 42) equipped with a fulcrum (38), the valve core (4) is equipped with an engagement element (46) for engaging with at least one of the arms (41, 42) for integral movement, the pin (47) is in contact with the pair of arms (41, 42) such that the movement of the pin (47) corresponds to the movement of the servo control device, wherein the reciprocating distance of the pair of arms (41, 42) increases accordingly depending on the position of the servo control device.The position feedback of the actual position of the servo control device is constituted by the reciprocating distance of the pair of arms (41, 42) of the pin (47).

[0019] Preferably, the valve (1) includes an inlet pipe (27) for pressurizing fluid, a first control pipe (29) and a second control pipe (28), the first control pipe (29) being in fluid communication with a first half of the cylinder (45), and the second control pipe (28) being in fluid communication with a second half of the cylinder (45), the inlet pipe (27) being located on the body of the valve (1) and between the first control pipe (29) and the second control pipe (28).

[0020] Preferably, the first solenoid (9) is positioned opposite to the second solenoid (10) on the valve (1), the first solenoid (9) is configured to apply a pushing force to move the valve core (4) in the first position to connect the fluid communication between the inlet pipe (27) and the first control pipe (29), and the second solenoid (10) is configured to apply a reverse pushing force to move the valve core (4) in the second position to connect the fluid communication between the inlet pipe (27) and the second control pipe (28).

[0021] Preferably, the first solenoid (9) independently controls the displacement increase and decrease commands relative to the second solenoid (10) in the first operating state of the pump, and the second solenoid (10) independently controls the displacement increase and decrease commands relative to the first solenoid (9) in the second operating state of the pump.

[0022] Preferably, the displacement change control device (21) is configured such that the connection device of the displacement change device of the pump (19) causes the flow to reverse between the first port (35) and the second port (36) of the pump (19) so that the flow passes between the positive displacement corresponding to the first position of the valve core (4) and the negative displacement corresponding to the second position of the valve core (4), and the rotation direction of the pump (19) remains the same even when the flow between the ports (35, 36) is reversed.

[0023] Preferably, the first operating state of the pump corresponds to the positive displacement under independent control of the first solenoid (9) relative to the second solenoid (10), while the second operating state of the pump corresponds to the negative displacement under independent control of the second solenoid (10) relative to the first solenoid (9).

[0024] Preferably, the first solenoid (9) is a proportional solenoid used to push the valve core (4) to the first position, which is proportional to the control current of the first output of the control unit.

[0025] Preferably, the second solenoid (10) is a proportional solenoid used to push the valve core (4) to a second position, which is proportional to the control current of the second output of the control unit.

[0026] Preferably, the valve (1) includes a gap (16) obtained in the space between the valve seat (3) and the valve core (4), the gap (16) communicating with pipes (27, 28, 29), the valve core (4) being provided with flow blocking elements (25, 26), the flow blocking elements being positioned such that, in the neutral position, the first blocking element (26) blocks the fluid communication between the inlet pipe (27) and the first control pipe (29), while the second blocking element (25) blocks the fluid communication between the inlet pipe (27) and the second control pipe (28), in the first position for delivering fluid to the first half of the cylinder (45), The first blocking element (26) is positioned such that the inlet pipe (27) and the first control pipe (29) are in fluid communication through the gap (16), while the second blocking element (25) blocks the fluid communication between the inlet pipe (27) and the second control pipe (28). In the second position for delivering fluid to the second half of the cylinder (45), the second blocking element (25) is positioned such that the inlet pipe (27) and the second control pipe (28) are in fluid communication through the gap (16), while the first blocking element (26) blocks the fluid communication between the inlet pipe (27) and the first control pipe (29).

[0027] Preferably, each of the first blocking element (26) and the second blocking element (25) consists of a double annular protrusion obtained on the valve core (4), the double annular protrusion forming double teeth, which closes the corresponding pipe on both sides of the pipe itself when the valve core (4) is in the neutral position, the double annular protrusion allowing flow to the corresponding pipe and blocking flow outside the gap (16) connecting the pipes.

[0028] Preferably, the cylinder (45) is a double-acting cylinder with a through rod, wherein the through rod is integral with the piston (18), and the through rod constitutes the connecting device of the displacement changing device of the pump (19).

[0029] Preferably, the control unit further includes a temperature sensor for detecting the temperature of the pump, and the control unit is provided with another input for the temperature signal from the temperature sensor of the pump and temperature control logic for generating an alarm signal and / or reducing or stopping the pump speed if the detected temperature is higher than an intervention threshold.

[0030] Preferably, the control unit is made in the form of an electronic card integrated on the pump (19) body, and the temperature sensor for temperature detection is mounted on the card. The card is installed in contact with the pump body so that the temperature sensor is in direct contact with the pump body itself.

[0031] Preferably, the device includes a remote control device (11) having a communication channel with the control unit. The remote control device (11) includes at least one operator interface element for controlling displacement increase (13') and an operator interface element for controlling displacement decrease (13"), wherein the operator interface element for controlling displacement increase (13') is connected to the displacement increase input of the control unit through the communication channel, and the operator interface element for controlling displacement decrease (13") is connected to the displacement decrease input of the control unit through the communication channel.

[0032] Preferably, the remote control device (11) includes a status indicator (8) for visualizing status signals and alarm signals, the status indicator (8) being connected to the corresponding signal output of the control unit via the communication channel.

[0033] Preferably, the status indicator (8) is selected between an indicator light and a visualization display for visualizing the signal output of the control unit.

[0034] Preferably, the communication channel is selected from among the wireless communication channel, the wired communication channel, and the serial communication bus type communication channel.

[0035] Preferably, the control device (11) is made in the form of a touch screen device and is provided with a program for the processor that constitutes a human-machine interface.

[0036] The present invention also provides a control method for a hydraulic pump (19), wherein the pump is provided with a displacement changing device and a control system, characterized in that the control system of the hydraulic pump (19) is the control system of the hydraulic pump (19) described above, and the method includes the following steps:

[0037] - An operator receives a displacement change instruction, which is selected between a displacement increase instruction and a displacement decrease instruction;

[0038] - Activate the corresponding displacement change command input of the control unit, wherein the displacement increase command causes the displacement increase input of the control unit to be activated, and the displacement decrease command causes the displacement decrease input of the control unit to be activated;

[0039] -The displacement change command is formulated by the control unit;

[0040] -Activate the corresponding displacement change control output of the control unit;

[0041] in,

[0042] The valve (1) includes a body (2) having a conduit for alternately supplying fluid to a first or second half of a cylinder (45), the conduit including an inlet conduit (27), a first control conduit (29), and a second control conduit (28). The valve (1) includes a valve core (4) movable within a valve seat (3) between at least three positions: a neutral position for preventing fluid flow to the cylinder (45), a first position for supplying fluid to the first half of the cylinder (45), and a second position for supplying fluid to the second half of the cylinder (45). The valve core (4) is associated with a return flow mechanism. The system includes a position detection device (39) for a servo control device, for position feedback of the actual position of the servo control device, and the control unit includes logic for current control of a first output and a second output based on the feedback of the position detection device (39). The method includes a phase for controlling the current of the first output and the second output based on the feedback of the position detection device (39) of the servo control device to set the actual position of the servo control device.

[0043] Preferably, if the valve core (4) is in the neutral position, the activation phase of the corresponding displacement change control output of the control unit is the phase of increasing the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement increase command receiving phase.

[0044] - If the valve core (4) is in the neutral position, the activation phase of the corresponding displacement change control output of the control unit is the phase of increasing the control current of the second solenoid (9). In this case, the displacement change command receiving phase is the displacement decrease command receiving phase.

[0045] Preferably, if the valve core (4) is in the first position, the activation phase of the corresponding displacement change control output of the control unit is the phase of increasing the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement increase command receiving phase.

[0046] - If the valve core (4) is in the first position, the activation phase of the corresponding displacement change control output of the control unit is the reduction phase of the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement reduction command receiving phase.

[0047] Preferably, if the valve core (4) is in the second position, the activation phase of the corresponding displacement change control output of the control unit is the reduction phase of the control current of the second solenoid (10). In this case, the displacement change command receiving phase is the displacement increase command receiving phase.

[0048] -If the valve core (4) is in the second position, the activation phase of the corresponding displacement change control output of the control unit is the phase of increasing the control current of the second solenoid (10). In this case, the displacement change command receiving phase is the displacement decrease command receiving phase.

[0049] Preferably, the control system for the hydraulic pump (19) is the control system for the hydraulic pump (19) described above, characterized in that the method further includes a stage of acquiring the temperature of the pump through a temperature sensor to detect the temperature of the pump, and a stage of verifying the temperature of the pump, and an additional stage of generating an alarm signal and / or reducing or stopping the pump speed if the detected temperature is higher than an intervention threshold.

[0050] The present invention also provides a hydraulic pump (19) with a displacement changing device, wherein the pump (19) includes a displacement changing device, the pump is provided with a control system, the control system including a control device (21) for changing the displacement, characterized in that the control system is a control system for a hydraulic pump (19) as described above, and is integrated into the pump structure.

[0051] Preferably, the control unit includes a program for the processor to execute the control method of the hydraulic pump (19) as described above. Advantages of the present invention

[0052] The solution according to the invention, through a considerable inventive contribution, constitutes a direct and non-negligible technological advancement, and has various advantages.

[0053] The variable displacement hydraulic pump with an improved control system according to the invention is advantageously independent of oil temperature and ambient temperature.

[0054] Furthermore, the system is more sensitive to, more accurate, and more reliable in responding to given instructions.

[0055] Variable displacement hydraulic pumps with improved control systems also allow for programmable custom operation. For example, the operator can select an operating mode in which issued commands are more or less responsive, in which steps of increasing or decreasing displacement have a greater effect, resulting in higher speeds or lower efficiency, and in which greater precision can be achieved.

[0056] Advantageously, stop and displacement change commands can be made independent of each other.

[0057] A significant advantage is that the system of the present invention also allows for diagnostic operations, wherein the system status is visualized and potential faults or anomalies are reported to the operator in real time.

[0058] In addition, the system allows for continuous monitoring and storage of oil temperature.

[0059] The system is reverse-activated, therefore the actual displacement set on the pump is always known.

[0060] Compared to known systems, this simplification reduces the number of components and cost while improving reliability.

[0061] This greatly simplifies machining and reduces the cost of the pump. Attached Figure Description

[0062] The following description of the embodiments and solutions is intended to be considered a non-limiting example of the invention, with reference to the accompanying drawings, wherein:

[0063] Figure 1 A schematic diagram showing the components of a variable displacement hydraulic pump and related controls in the prior art.

[0064] Figure 2 This refers to existing variable displacement hydraulic pumps and related controls.

[0065] Figure 3 express Figure 2 Details of the variable displacement hydraulic pump.

[0066] Figure 4 A schematic diagram showing the components and related controls of the variable displacement hydraulic pump of the present invention.

[0067] Figure 5 This invention relates to a variable displacement hydraulic pump and related control.

[0068] Figure 6 This describes a part of the control system of the variable displacement hydraulic pump of the present invention, as well as the related control in the static state.

[0069] Figure 7 yes Figure 6 Enlarged view of section A.

[0070] Figure 8 This describes a part of the control system of the variable displacement hydraulic pump of the present invention and related controls in the first operating state.

[0071] Figure 9 yes Figure 8 Enlarged view of section B.

[0072] Figure 10 This describes a part of the control system of the variable displacement hydraulic pump of the present invention and related controls in a second operating state.

[0073] Figure 11 yes Figure 10 Enlarged view of section C.

[0074] Figure 12 The static state of the system of the present invention is shown.

[0075] Figure 13 The instructions of the system of the present invention in a first direction and a first operating state are shown.

[0076] Figure 14 The instructions for the system of the present invention in a first direction and a second operating state are shown.

[0077] Figure 15 The instructions for the system of the present invention in the second direction are shown.

[0078] Figure 16 The instructions of the system of the present invention in a first direction are illustrated schematically.

[0079] Figure 17 The instructions of the system of the present invention in the second direction are illustrated schematically.

[0080] Figure 18 A cross-section of a portion of the pump incorporated into the system of the present invention is shown.

[0081] Figure 19 This is an exploded view of the pump in conjunction with the system of this invention. Summary of the Invention

[0082] This invention relates to a variable displacement hydraulic pump with an improved control system.

[0083] Solutions based on existing technologies ( Figure 1 , Figure 2 , Figure 3The control system used allows for changes in the displacement of the variable displacement pump and also allows for reversal of the rotation direction of the drive system controlled by the pump itself. Known solutions specify that the pump is controlled by a prior art control system (20), which consists of a set of valves including:

[0084] - Drive valve (1);

[0085] - Control valve (6);

[0086] -Bypass valve (22).

[0087] Existing technology ( Figure 1 , Figure 2 , Figure 3 The control system (20) also includes a series of valve-driven solenoids, wherein:

[0088] - Displacement increasing solenoid (43) and displacement decreasing solenoid (44), which are applied to drive valve (1);

[0089] - Stop solenoid (5), which is used in bypass valve (22).

[0090] Therefore, in the existing technical solution, the control system (20) consists of a set of three solenoids (5, 43, 44) that drive two spool valves. The two solenoids (43, 44) act on the valve cores, and an additional stop solenoid (5) acts on another different valve, namely the bypass valve.

[0091] As described above, this type of control system (20) allows manufacturers of vehicles equipped with pumps (e.g., concrete mixers) to directly connect the pump ( Figure 1The remote control device (11) can be configured, for example, in the form of a button panel that allows the operator to control and command the pump, thereby enabling the machine to perform its intended function. The remote control device (11) can be shaped in various ways to meet customer needs. For example, in a non-limiting application on a truck mixer, the remote control device (11) may include a displacement increase button (13') and a displacement decrease button (13'') for adjusting the pump's displacement, allowing the displacement to be increased or decreased by a command pulse in one or the opposite direction. In existing solutions, the pump's displacement increases or decreases depending on the degree to which either the displacement increase button (13') or the displacement decrease button (13") is pressed, until the respective button is released, at which point it remains at the set value. The pump is always symmetrical, i.e., it has a maximum positive displacement (e.g., 90cc) and a maximum negative displacement (e.g., -90cc). By actuating the buttons, the displacement can gradually transition from positive to negative, through a zero state. Zero corresponds to the pump's stopped state, and in the exemplary and non-limiting application to a concrete mixer, it corresponds to the stopped state of the concrete mixer's drum. The maximum displacement (e.g., 90cc) corresponds to the maximum speed in one direction, and the minimum displacement (e.g., -90cc) corresponds to the maximum speed in the opposite direction. To zero the displacement, the operator manually reaches zero by operating the button and visually judges when the drum stops. In addition, there is an emergency button (12), which, as will be explained, also serves as an emergency displacement zeroing button for stopping the pump.

[0092] The RE-type control system (20) was manufactured ( Figure 2 , Figure 3 The control block is directly mounted on the variable displacement pump (19). As mentioned above, in known systems, the RE-type control system (20) is highly dependent on oil temperature, which in turn depends on ambient temperature. This makes the commands of the known system non-repeatable and further raises issues related to the pump's zeroing phase, in which additional components are needed to ensure the restoration of the pump to the neutral conditions it was in when it was stopped.

[0093] In fact, the existing RE-type control system (20) consists of three solenoids, two of which, namely the displacement increasing solenoid (43) and the displacement decreasing solenoid (44), are applied to the same cartridge-type drive valve (1).

[0094] Two solenoids acting on the drive valve (1), namely the displacement increasing solenoid (43) and the displacement decreasing solenoid (44), are installed to provide two opposing magnetic fields: one solenoid moves the valve to one side, opening one pipe, while the other solenoid moves the valve in the opposite direction, opening the other pipe. The valve returns to the center and neutral position, keeping both pipes closed. By opening either pipe, the drive valve (1) causes oil to flow to both sides of the control valve (6), causing it to move. This movement, in turn, causes the piston (18) to move, which acts directly on the displacement changing cylinder (45), a component commonly referred to as the servo control piston. The responsiveness of the command, i.e., the time from maximum displacement to zero, or from maximum displacement clockwise to maximum displacement counterclockwise, depends on the size of some throttle valves located on the path that the oil follows as it moves from the drive valve (1) to the control valve (6). The same applies when a rotation stop or emergency command is issued. Therefore, the system is limited by these components and cannot achieve some of the flexibility sought by customers. In particular, there cannot be a significant acceleration and deceleration slope because the oil must travel the same path in two different directions, passing through the same throttle valve in both directions.

[0095] The existing RE-type control system (20) also includes a stop solenoid (5) that acts on an electric bypass valve (22), which causes a stop under normal or emergency conditions. The stop solenoid (5) acts on the bypass valve (22), which is an on / off valve that opens the circulating oil through a bypass path. This causes the displacement to return to zero, thereby causing the main oil flow to return to zero. The stop solenoid (5) is activated by a special button, an emergency button (12), on the remote control device (11). The operator can return the displacement to zero by pressing this button. After releasing the button, the displacement automatically returns to its original value because pressing the emergency button (12) does not cause the proportional control valve (6) to actuate, maintaining a memory effect. This occurs because the stop and emergency systems constitute a bypass system in all respects and do not interfere in any way with the upstream system components, which all maintain the same configuration previously set by the operator.

[0096] The existing RE-type control system (20) also includes a handle (7), such as a lever, for manual operation of the pump in case of emergency, which acts mechanically on the control valve (6).

[0097] Because of its temperature dependence, and given that commands to increase and decrease displacement have different effects on the system, the pump cannot be zeroed by the two solenoids acting on the drive valve (1), namely the displacement increase solenoid (43) and the displacement decrease solenoid (44). In fact, by issuing a series of displacement increase commands followed by the same number of displacement decrease commands, the system will not return to the initial zero position.

[0098] This also depends on the fact that the existing RE-type control system (20) is not reversible, and the operator gradually increases and decreases the displacement without truly knowing what the actual set displacement is, because it is obtained through pulse commands acting on the actuating solenoids (43, 44), whose behavior is not identical to that of the valve. Therefore, the lack of backtracking involves a lack of control over the true state of the system and an inability to know the actual displacement set by the operator.

[0099] The variable displacement pump (19) of the present invention Figure 4 , Figure 5 , Figure 6 , Figure 8 , Figure 10 The system includes an innovative control system comprising a control unit (17) which is advantageously integrated directly into the body of the variable displacement pump (19) in the form of an electronic card. The electronic card converts the control digital input from the control button panel (11) into a current-modulated signal that powers two solenoids, consisting of a first solenoid (9) and a second solenoid (10) controlled by proportional electronics.

[0100] Advantageously, the proportional first solenoid (9) and second solenoid (10) generate thrust proportional to the delivered current, and in this way, the actual position of the valve components can be controlled more precisely, thereby controlling the set displacement. In fact, the control unit not only generates the control current of the first solenoid (9) and second solenoid (10), but also acquires the actual control current signal present when transmitted to each of the two solenoids (9, 10). It verifies the correspondence between the set current value and the relative set point, and corrects the actual measured value according to the feedback signal to make it correspond to the set point.

[0101] In fact, because these are two proportional solenoids, the current feedback of the system allows for precise adjustment of the current, making the final behavior of the hydraulic system unaffected by temperature. The problem in this regard is the thermal drift of the solenoids due to temperature variations. In fact, the resistance of the solenoids increases with rising temperature. In existing systems, the power on the displacement increasing and decreasing solenoids (43, 44) remains constant, rather than the current, by not providing current feedback. Therefore, during operation, as each of the two displacement increasing and decreasing solenoids (43, 44) heats up, its resistance increases, and thus, the current absorbed decreases because the resistive effect is superior to the inductive effect. The result of this effect is a reduction in pump displacement. Conversely, by maintaining a constant current, the system self-regulates to compensate for the thermal drift effect of the first solenoid (9) and the second solenoid (10). As the temperature rises, the system of the present invention will respond by increasing the power injected into either the first solenoid (9) or the second solenoid, thereby compensating for the increased losses due to the Joule effect. A control unit (17) in the form of an electronic card is able to manage component aging through the same system.

[0102] The control unit (17) in the form of an electronic card is equipped with at least the following inputs:

[0103] - Displacement increase command;

[0104] - Displacement reduction command;

[0105] -Stop command;

[0106] - The speed of the hydraulic motor connected to the pump is detected by a sensor;

[0107] - Pump temperature, measured by a temperature sensor mounted on the card and in direct contact with the pump;

[0108] - CAN communication port, used to connect to PC or other electronic peripherals.

[0109] The control unit (17) in the form of an electronic card is equipped with at least the following outputs:

[0110] - Current output of the first solenoid (9);

[0111] - Current output of the second solenoid (10).

[0112] The control logic for the current output is of the PID type and is used to control the current supplied to each of the first solenoid (9) and the second solenoid (10), as described below in this specification.

[0113] The first and second solenoids (9, 10) act directly on the two valves (23, 24). The first solenoid (9) acts on the first valve (23), and the second solenoid (10) acts on the second valve (24). The second valve (24) directly pushes the main valve core (4) in the opposite direction.

[0114] Each valve (23, 24) includes an internal valve piston that is moved by the magnetic force generated by the corresponding solenoid (9, 10). Each of the valves (23, 24) further includes a valve stem connected to the internal valve piston, wherein the valve stem acts on the valve core (4). The proportionality of the instructions given by the control unit (17) is obtained by using current control, since a certain force applied to the valve stem of each valve (23, 24) corresponds to a certain current applied to each solenoid (9, 10), which is transmitted from the valve stem to the valve core (4) under the balancing force of a spring (37), which is linear and will cause the pipe to open according to the law that is proportional to the force, and therefore proportional to the applied current, which is the control current of the solenoid (9, 10) applied by the control unit (17).

[0115] The body (2) also includes discharge pipes, which include a first discharge pipe (33), a second discharge pipe (34), a third discharge pipe (30), a fourth discharge pipe (31), and a fifth discharge pipe (32). When the piston (18) moves to the right ( Figure 10 When (), the third discharge pipe (30), the fourth discharge pipe (31), and the fifth discharge pipe (32) discharge return oil from the cylinder of the displacement change control device (21). Figure 8 When the piston (18) moves to the left, the gap (16) also performs the same function. The first discharge pipe (33) and the second discharge pipe (34) position the head of the valve core (4) on the opposite side of the thrust solenoid to avoid the syringe effect, that is, the chamber corresponding to the head exerts a suction effect on the valve core (4) to counteract the force of the opposite solenoid.

[0116] Advantageously, the system provides the following function: according to this function, the drive valve (1) maintains a set displacement until the relative solenoid selected between the first solenoid (9) and the second solenoid (10) remains energized, and the current on it is kept constant by reverse operation control.

[0117] Compared with existing control systems (20)( Figure 1 , Figure 2 , Figure 3In contrast, neither the bypass valve (22) nor the control valve (6) exists in the control system (20) of the present invention, because only the drive valve (1) has a corresponding main valve core (4) which is capable of performing all the same functions, thanks to the configuration of the control unit (17) and the first solenoid (9) and the corresponding first valve (23), the second solenoid (10) and the corresponding second valve (24).

[0118] Advantageously, and in contrast to existing solutions, in the solution of this invention, the given hydraulic commands cannot support themselves and require a driving current to operate. Thus, by eliminating the current, the system returns to a neutral position, also gaining the advantage of reducing the number of components, while improving system safety and reliability, and avoiding the problems of existing solutions where an interruption is achieved through a bypass but the system is not zeroed, and the system maintains its displacement setting before the bypass is activated.

[0119] Due to the configuration of the control unit (17) and drive valve (1) of the system of the present invention, all the functions of the prior art control system (20) can be replicated, but with improved and additional functions. For example, the customized programming settings allow the operator to select, for instance, an operating mode where the given instructions are more or less responsive, where the steps of increasing or decreasing displacement have a greater impact on obtaining greater speed or a smaller impact on obtaining higher precision. Each parameter can be configured. Therefore, the slopes of the acceleration, deceleration, and stop lines can be modified at will without any interdependence. This feature allows overcoming the limitations present in prior art systems where the slopes are mutually constrained. The behavior of the system can be fully customized. These functions are obtained by properly programming the control unit (17) in the form of an electronic card placed on the pump. For example, for the same input signal at the displacement increase input, different current slopes can be obtained on the output solenoid selected between the first solenoid (9) and the second solenoid (10), which is not possible in prior art systems.

[0120] It can be connected to the control unit (17) via a wireless communication channel in the form of an electronic card, for example, from an application on a smartphone or a PC. Once connected to the control unit (17) via the wireless communication channel, it can:

[0121] - Send configuration parameters;

[0122] - Access diagnostic data stored in memory;

[0123] - Update the firmware of the control unit (17) in the form of an electronic card.

[0124] The radio module can also be integrated into the control unit for connectivity via a 4G / LTE network. This connection allows for remote access to machine parameters. Therefore, the same parameters can be managed via wireless communication channels without requiring the device to be near the machine.

[0125] Furthermore, the stop and displacement change commands can be independent of each other. These functions are achieved by appropriately programming the control unit (17) located on the pump. For example, in the case of a truck mixer application, the drum rotation stop command can correspond to a specific slope in which the current in the solenoids (9, 10) is directed toward zero. The command to increase or decrease the displacement can correspond to another independent slope, corresponding to different responsiveness.

[0126] The system of this invention also offers the significant advantages of allowing diagnostic operations, visualizing system status, and reporting any faults or anomalies to the operator in real time. In fact, the control unit (6) is able to understand:

[0127] • Button panel short circuit;

[0128] • By detecting overcurrent in the current feedback measurement, a short circuit exists on one or both of the two solenoids selected between the first solenoid (9) and the second solenoid (10);

[0129] • An open-circuit side exists on one or both of the two solenoids selected between the first solenoid (9) and the second solenoid (10) by detecting zero current in the current feedback measurement;

[0130] • The solenoid selected between the first solenoid (9) and the second solenoid (10) is damaged, resulting in a short circuit.

[0131] These functions are achieved by appropriately programming the control unit (17) on the pump based on the data (operating temperature, current setpoint, actual current value) read from the control unit (17).

[0132] In addition, a status indicator (8), such as an indicator light or a diagnostic display, can be integrated into the remote control device (11) to view the detected fault alarms, the actual set displacement, etc.

[0133] In addition, the control unit (6) is able to verify the machine's operating temperature and keep it in a safe state. In fact, the system also allows for continuous monitoring and storage of oil temperature, which can be used to provide indication on a status indicator in the form of an indicator light or a diagnostic display.

[0134] The control unit (17) in the form of an electronic card is advantageously equipped with a temperature sensor that is directly inserted into the card and in contact with the pump surface. The control unit (17) can be programmed to perform appropriate actions, such as, but not limited to, illuminating appropriate indicator lights on the status indicator (8) on the control unit (17) itself and / or the remote control device (11) or reducing the pump displacement, to reduce the power consumed in the hydraulic circuit, if the temperature reaches a certain value and remains there for a certain period of time. All of this is achieved through software programming of the card that constitutes the control unit (17).

[0135] The control unit (17) can also receive input signals from the speed sensor on the hydraulic motor connected to the pump (19). For concrete mixer applications, the control unit (17) can be programmed to create a closed-loop control cycle that keeps the drum's rotational speed at the value set via the button panel (11), unaffected by the rotational speed of the diesel engine or hydraulic pump. In the example of a truck mixer application, this allows for maintaining a constant mixing speed during concrete transport, offering significant advantages in terms of product quality. In this case, the control unit would be equipped with a speed signal input as a second feedback signal to control the speed of the hydraulic motor connected to the pump, controlling the displacement of the pump (19). Therefore, the control phase of the solenoid current can be adjusted based on the speed of the hydraulic motor, rather than the position feedback of the piston (18) of the servo control unit, and the rotational speed of the hydraulic motor depends on the position of the valve core (3).

[0136] The first valve (23) and the second valve (24) are obtained within the body (2). Within the body, there is a valve seat (3) for sliding the main valve core (4), the function of which will be explained in the following description.

[0137] The reference system is at rest ( Figure 6 , Figure 7 , Figure 12 Functions under ) Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 The first solenoid (9) and the second solenoid (10) are not controlled by the current of the control unit (17), and the main valve core (4) remains in the neutral center position, with the fluid transfer block located between the inlet pipe (27) and the control pipes (28, 29). Thus, the displacement changing device (21) remains in the neutral position. Blockage is achieved in the following manner:

[0138] - A first blocking element (26) that blocks the fluid communication of the gap (16) between the inlet pipe (27) and the first control pipe (29);

[0139] - A second blocking element (25) that blocks the fluid communication between the inlet pipe (27) and the second control pipe (28) and the gap (16).

[0140] The first blocking element (26) and the second blocking element (25) have a shape with double annular protrusions obtained on the main valve core, forming double teeth on the main valve core, and closing the corresponding pipes on both sides of the pipe itself. The main valve core (4) is inserted into the valve seat (3) to form a gap (16), which is used to allow the pressurized oil inlet pipe (27) to be alternately fluidly connected to the first control pipe (29) or the second control pipe (28). In this case ( Figure 12 When the main valve core (4) is in the neutral position, the fluid filling pressure, that is, the oil filling pressure, will not be transmitted to the displacement change device (21). For example, at 2000 rpm, the air filling pressure in the inlet pipe (27) may be 28 bar, and in a static state, the maximum discharge pressure in the first pipe (29) and the second pipe (28) may be about 2 bar.

[0141] In the first working state ( Figure 8 , Figure 9 The first solenoid (9) is electrically controlled by the control unit (17), while the second solenoid (10) is uncontrolled. In this case, the main valve core (4) moves relative to the neutral center position to form fluid communication through the gap (16) between the inlet pipe (27) and the first control pipe (29). In this way, the displacement changing device (21) is a double-acting cylinder (45) with a through rod, which is fluid-controlled by moving the piston (18) connected to the pump through the first half of the cylinder (45) separated by the piston (18) to control the increase of displacement in the first direction, which is represented by positive displacement. After the first solenoid (9) is activated by the control unit (17), it causes the main valve core (4) to move to the right in Figure (9). Figure 8 , Figure 9 This opens the connection between the pressurized oil inlet pipe (27) and the first pipe (29). Therefore, the movement of the displacement control device (21)... Figure 8 This occurs along the first corresponding direction of movement. In this configuration ( Figure 16 In a concrete mixer, with the pump rotating in the same direction, there is a first configuration of the flow direction in the first port (35) and the second port (36). For example, in an exemplary and non-limiting application on a concrete mixer, the first flow direction configuration in the first port (35) and the second port (36) causes the drum to rotate in the first rotation direction of the drum. According to the instructions issued by the operator via the remote control device (11), the higher the command current delivered by the control unit (17), the larger the displacement set on the pump, and the higher the rotational speed in the first direction. The main valve core (4) is connected to ( Figure 12 , Figure 13 , Figure 14 The fork (40) comprises a first arm (41) and a second arm (42), which are hinged at a fulcrum (38) and equipped with a return spring (37). As the main valve core (4) moves, the arms (41, 42) reciprocate and space apart as the spring (37) is loaded. The final position is determined by the balance between the force applied by the first solenoid (9) and the restoring force of the spring (37). The system of the fork (40) has a device for detecting the position (39) of the servo control piston (18), which generates feedback to achieve the displacement actually set in the first operating state, which corresponds to the first configuration of flow in the port consisting of the first port (35) and the second port (36). In this case, the displacement is indicated as a positive displacement in order to indicate that flow control occurs in the first configuration between the first port (35) and the second port (36). In this way, the control unit (17) sets the command current output based on the feedback from the position detection device (39), which is relative to the actual position of the servo control device, and therefore corresponds to the feedback of the actual positive displacement set relative to the first working state of rotation in the first direction. Based on this feedback, the control unit (17) can control the control current of the first solenoid (9) until the desired actual position of the servo command device and the main valve core (4) is reached, setting the desired positive displacement, regardless of the thermal drift of the solenoid or component aging. In addition, in this way, a feedback signal indicating the arrival of the return to the stop condition can also be provided. When a stop command is issued, the current supply on the first solenoid (9) is interrupted, the force applied by the first solenoid to the main valve core (4) is interrupted, and under the action of the spring (37), the main valve core returns to the initial position, stopping the pump.

[0142] In the second working state ( Figure 10 , Figure 11 In this case, the first solenoid (9) is uncontrolled, while the second solenoid (10) is electrically controlled by the control unit (17). In this case, the main valve core (4) moves relative to the neutral center position to form fluid communication through the gap (16) between the inlet pipe (27) and the second control pipe (28). In this way, the displacement changing device (21) is a double-acting cylinder (45) with a through rod, fluidly controlled by the piston (18) passing through the second half of the cylinder (45) separated by the piston (18), moving the piston (18) connected to the pump to control an increase in displacement in the second direction, represented by a negative displacement. The second solenoid (10), after being activated by the control unit (17), causes the main valve core (4) to move to the left in Figure (11). Figure 10 , Figure 11 This opens the connection between the pressurized oil inlet pipe (27) and the second pipe (28). Therefore, the movement of the displacement control device (21)... Figure 10 ) proceeds along the corresponding second direction of movement. In this configuration ( Figure 17 In the first port (35) and the second port (36), there is a second flow direction configuration, which is opposite to the configuration obtained by controlling the first solenoid (9). The second flow direction configuration in the first port (35) and the second port (36) Figure 17 In this configuration, the pumps rotate in the same direction, and there are second flow direction configuration ports in the first port (35) and the second port (36). For example, in an exemplary and non-limiting application on a concrete mixer, this first flow direction configuration in the first port (35) and the second port (36) causes the drum to rotate in the second rotation direction of the drum. According to the instructions issued by the operator via the remote control device (11), the higher the control current delivered by the control unit (17), the larger the displacement set on the pump, and the higher the speed in the second direction. The main valve core (4) is connected to ( Figure 15 The fork (40) comprises a first arm (41) and a second arm (42), which are hinged at a fulcrum (38) and equipped with the aforementioned return spring (37). As the main valve core (4) moves, the arms (41, 42) reciprocate and space apart as the spring (37) is loaded. The final position is determined by the balance between the force applied by the second solenoid (10) and the restoring force of the spring (37). On the system of the fork (40), there is a position detection device (39) for the piston (18) of the aforementioned servo control device, which generates feedback to achieve the actually set displacement. In this case, in order to indicate that flow control occurs in the second configuration between the first port (35) and the second port (36), the displacement is indicated as a negative displacement. Thus, the control unit (17) sets the control current output based on the feedback from the position detection device (39), which is relative to the actual position of the servo control device. Therefore, this feedback corresponds to the feedback of the actual negative displacement set relative to the second working state of rotation in the second direction. Based on this feedback, the control unit (17) can control the control current of the second solenoid (10) until the desired actual position of the servo command device and the main valve core (4) is reached, setting the desired negative displacement regardless of thermal drift of the solenoid or component aging. In addition, in this way, a feedback signal indicating the arrival of the return to the stop condition can also be provided. When a stop command is issued, the current supply on the second solenoid (10) is interrupted, the force applied by the second solenoid to the main valve core (4) is interrupted, and under the action of the spring (37), the main valve core returns to the initial position, stopping the pump.

[0143] Regarding the position detection device (39), it includes ( Figure 18 Pin (47) is connected to the swashplate of the pump via lever (48), and the tilt of the swashplate limits the pump's displacement.

[0144] Pump (19) as a whole ( Figure 19 The pump includes a first half-shell (51) and a second half-shell (52) that surround and support all components of the pump, including the plate assembly (49), shaft (50), rotor (53) associated with the corresponding auxiliary pump or cycloidal pump (54), distributor plate (55) and flange (56).

[0145] Referring to the aforementioned functions and remote control device (11), the displacement increase button (13') and displacement decrease button (13") for adjusting pump displacement allow the displacement to be increased or decreased by a command pulse in one or the opposite direction.

[0146] For example, from a state of rest ( Figure 6 , Figure 7 At the beginning, repeatedly pressing the displacement increase button (13') will activate the first solenoid (9), thus the control current supplied by the control unit (17) to the first solenoid (9) will gradually increase, thereby causing the main valve core (4) to gradually move to the right. Figure 8 , Figure 9 As the displacement value gradually increases, a positive displacement with a gradually increasing module value is obtained. In this case, by acting on the displacement reduction button (13"), the control current supplied by the control unit (17) to the first solenoid (9) will decrease, thereby causing the main valve core (4) to gradually move to the left. Figure 8 , Figure 9 The corresponding positive displacement module value gradually decreases to zero. Once the neutral condition is reached, further pressure action on the displacement reduction button (13") involves the activation of the second solenoid (10), so the control current supplied by the control unit (17) to the second solenoid (10) will gradually increase, thereby causing the main valve core (4) to gradually move to the left. Figure 10 , Figure 11 As the displacement value gradually increases, a negative displacement with a gradually increasing module value is obtained. In this case, by actuating the displacement increase button (13"), the control current supplied by the control unit (17) to the second solenoid (10) will decrease, thereby causing the main valve core (4) to gradually move to the right. Figure 10 , Figure 11 As a result, the corresponding negative displacement module value gradually decreases to zero.

[0147] Finally, the present invention relates to a control system (1, 17, 21) for a hydraulic pump (19), wherein the pump is equipped with a displacement changing device, the system (1, 17, 21) includes a displacement changing control device (21) equipped with a servo control device, wherein the cylinder (45) and piston (18) of the servo control device have a connecting device connected to the displacement changing device of the pump (19), the cylinder (45) includes a first half and a second half separated by the piston (18) for delivering pressurized fluid, causing the piston (18) to move in a first direction of motion and a second direction of motion opposite to the first direction, respectively. The system includes a control unit (17), a drive valve (1), and a first solenoid (9) and a second solenoid (10) for controlling the valve (1). The control unit (17) includes a displacement increase input and a displacement decrease input, a first output connected to the first solenoid (9), and a second output connected to the second solenoid (10). The valve (1) includes a body (2) equipped with conduits (27, 28, 29) for alternately delivering fluid to a first or second half of a cylinder (45). The valve (1) includes a valve core (4) movable within a valve seat (3) between at least three positions: a neutral position for preventing fluid flow to the cylinder (45), a first position for delivering fluid to the first half of the cylinder (45), and a second position for delivering fluid to the second half of the cylinder (45). The valve core (4) is connected to an elastic element (37) for returning to the neutral position. The first solenoid (9) and the second solenoid (10) are current-operated solenoids. The system (1, 17, 21) includes a position detection device (39) for a servo control device to provide position feedback on the actual position of the servo control device. The control unit (17) includes logic for controlling the current of the first and second outputs based on the feedback from the position detection device (39).

[0148] Preferably, the valve (1) includes an inlet pipe (27) for pressurizing fluid, a first control pipe (29) and a second control pipe (28), the first control pipe (29) being in fluid communication with a first half of a cylinder (45), and the second control pipe (28) being in fluid communication with a second half of a cylinder (45). The inlet pipe (27) is located on the body of the valve (1) between the first control pipe (29) and the second control pipe (28). A first solenoid (9) is positioned opposite to the second solenoid (10) on the valve (1). The first solenoid (9) is configured to apply a pushing force to move the valve core (4) in the first position to connect the fluid communication between the inlet pipe (27) and the first control pipe (29). The second solenoid (10) is configured to apply a reverse pushing force to move the valve core (4) in the second position to connect the fluid communication between the inlet pipe (27) and the second control pipe (28). The first solenoid (9) independently controls the increase and decrease of displacement commands relative to the second solenoid (10) in the first working state of the pump, and the second solenoid (10) independently controls the increase and decrease of displacement commands relative to the first solenoid (9) in the second working state of the pump.

[0149] The displacement change control device (21) is configured such that the connection device of the displacement change device of the pump (19) causes the flow between the first port (35) and the second port (36) of the pump (19) to reverse, so as to pass between the positive displacement corresponding to the first position of the valve core (4) and the negative displacement corresponding to the second position of the valve core (4), and the rotation direction of the pump (19) remains the same even when the flow between the ports (35, 36) is reversed.

[0150] The first operating state of the pump corresponds to a positive discharge rate under independent control of the first solenoid (9) relative to the second solenoid (10), while the second operating state of the pump corresponds to the negative discharge rate under independent control of the second solenoid (10) relative to the first solenoid (9).

[0151] The first solenoid (9) is a proportional solenoid used to push the valve core (4) to a first position, which is proportional to the control current of the first output of the control unit (17). The second solenoid (10) is a proportional solenoid used to push the valve core (4) to a second position, which is proportional to the control current of the second output of the control unit (17).

[0152] The valve (1) includes a gap (16) obtained in the space between the valve seat (3) and the valve core (4), the gap (16) communicating with pipes (27, 28, 29), the valve core (4) being equipped with flow blocking elements (25, 26), the flow blocking elements being arranged such that in a neutral position, a first blocking element (26) blocks the fluid communication between the inlet pipe (27) and the first control pipe (29), while a second blocking element (25) blocks the fluid communication between the inlet pipe (27) and the second control pipe (28), in the first part of the first half for conveying fluid to the cylinder (45). In a second position for delivering fluid to the second half of the cylinder (45), the first blocking element (26) is positioned such that the inlet pipe (27) and the first control pipe (29) are in fluid communication through the gap (16), while the second blocking element (25) blocks the fluid communication between the inlet pipe (27) and the second control pipe (28). Preferably, each of the first blocking element (26) and the second blocking element (25) consists of a double-ringed protrusion on the valve core (4) forming a double tooth. When the valve core (4) is in the neutral position, the protrusion closes the corresponding pipe on both sides of the pipe itself, allowing flow toward the corresponding pipe while blocking flow outside the gap (16) connecting the pipes.

[0153] The cylinder (45) is a double-acting cylinder with a through rod, wherein the through rod and the piston (18) are integral, and the through rod constitutes the connecting device of the displacement changing device of the pump (19).

[0154] The device (39) for detecting the position of the servo control device includes a pin (47) which is connected to the servo control device via a lever (48) such that movement of the pin (47) corresponds to movement of the servo control device.

[0155] An elastic element (37) for returning to the neutral position is disposed between a pair of arms (41, 42) equipped with a fulcrum (38), and a valve core (4) is provided with an engagement element (46) for engaging with the pair of arms (41, 42) for integral movement of the valve core (4) with at least one of the arms of the pair of arms (41, 42), the pair of arms preferably being configured to form a fork.

[0156] The pin (47) is in contact with the pair of arms (41, 42), such that the movement of the pin (47) corresponds to the movement of the servo control device. The reciprocating distance of the pair of arms (41, 42) increases accordingly based on the position of the servo control device, and this reciprocating distance constitutes position feedback of the actual position of the servo control device. Thus, the control unit sends a command to one of the two solenoids (9, 10), which instructs its own valve to control the movement of the valve core (4) acting on the servo control device. The lever moves with the servo control device and, by acting sequentially on an elastic element, moves the pin (47) inserted into the arm, thus altering the force exerted on the valve core (4) by the elastic element, as if it were mechanical feedback. The control unit then intervenes to control the output current, bringing the solenoid to the desired equilibrium state, with the spring corresponding to a certain output current, thus achieving feedback.

[0157] The system may also include a temperature sensor for detecting pump temperature, and the control unit (17) is equipped with another input for the temperature signal from the pump temperature sensor and temperature control logic for generating an alarm signal and / or reducing or stopping the pump speed if the detected temperature is higher than an intervention threshold. Therefore, the control unit (17) can be made in the form of an electronic card integrated on the pump (19) body, with the temperature sensor for temperature detection mounted on the card, and the card is installed in contact with the pump body so that the temperature sensor is in direct contact with the pump body itself.

[0158] The system may include a remote control device (11) equipped with a communication channel with a control unit (17). The remote control device (11) includes at least one operator interface element for controlling displacement increase (13') and an operator interface element for controlling displacement decrease (13"), wherein the operator interface element for controlling displacement increase (13') is connected to the displacement increase input of the control unit (17) via the communication channel, and the operator interface element for controlling displacement decrease (13") is connected to the displacement decrease input of the control unit (17) via the communication channel. For example, the remote control device (11) may include a status indicator (8) for visualizing status signals and alarm signals, the status indicator (8) being connected to the corresponding signal output of the control unit (17) via the communication channel. The status indicator (8) is selected from indicator lights and a visualization display for visualizing the signal output of the control unit (17). The communication channel is selected from wireless communication channels, wired communication channels, and communication channels implemented in the form of serial communication buses. The remote control device (11) can be made in the form of a touch screen device, equipped with an application or program for the processor that constitutes the human-machine interface.

[0159] The present invention also relates to a control method for a hydraulic pump (19), wherein the pump is equipped with a displacement changing device and a control system (1, 17, 21), the system (1, 17, 21) including a displacement changing control device (21), the displacement changing control device being equipped with a servo control device, the servo control device having a cylinder (45), the cylinder (45) including a piston (18), the piston (18) being provided with a connection device to the displacement changing device of the pump (19), the cylinder (45) including a portion separated by the piston (18). The system comprises a first half and a second half for conveying pressurized fluid, causing the piston (18) to move in a first direction of motion and a second direction of motion opposite to the first direction, respectively. The system includes a control unit (17), a drive valve (1), and a first solenoid (9) and a second solenoid (10) for controlling the valve (1). The control unit (17) includes a displacement increase input and a displacement decrease input, a first output connected to the first solenoid (9), and a second output connected to the second solenoid (10). The method includes the following steps:

[0160] - An operator receives a displacement change instruction, which is selected between a displacement increase instruction and a displacement decrease instruction;

[0161] -Activate the corresponding displacement change command input of the control unit (17), wherein the displacement increase command causes the displacement increase input of the control unit (17) to be activated, and the displacement decrease command causes the displacement decrease input of the control unit (17) to be activated;

[0162] - The displacement change command is formulated by the control unit (17);

[0163] -Activate the corresponding displacement change control output of the control unit (17).

[0164] In the system, the valve (1) includes a body (2) equipped with conduits (27, 28, 29) for alternately delivering fluid to a first or second half of a cylinder (45). The valve (1) includes a valve core (4) movable within a valve seat (3) between at least three positions: a neutral position for preventing fluid flow to the cylinder (45), a first position for delivering fluid to the first half of the cylinder (45), and a second position for delivering fluid to the second half of the cylinder (45). The valve core (4) is connected to an elastic element (37) for returning to the neutral position. Next, the first solenoid (9) and the second solenoid (10) are current-operated solenoids. The system (1, 17, 21) includes a position detection device (39) for the servo control device to provide position feedback on the actual position of the servo control device. The control unit (17) includes logic for current control of the first output and the second output based on the feedback from the position detection device (39). The method includes a phase for controlling the current of the first output and the second output based on the feedback from the position detection device (39) of the servo control device to set the actual position of the servo control device.

[0165] In the method:

[0166] -If the valve core (4) is in the neutral position, the activation phase of the corresponding displacement change command output of the control unit (17) is the increase phase of the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement increase command receiving phase.

[0167] - If the valve core (4) is in the neutral position, the activation phase of the corresponding displacement change command output of the control unit (17) is the increase phase of the control current of the second solenoid (9). In this case, the displacement change command receiving phase is the displacement decrease command receiving phase.

[0168] In the method:

[0169] -If the valve core (4) is in the first position, the activation phase of the corresponding displacement change command output of the control unit (17) is the increase phase of the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement increase command receiving phase.

[0170] - If the valve core (4) is in the first position, the activation phase of the corresponding displacement change command output of the control unit (17) is the reduction phase of the control current of the first solenoid (10). In this case, the displacement change command receiving phase is the displacement reduction command receiving phase.

[0171] In the method:

[0172] -If the valve core (4) is in the second position, the activation phase of the corresponding displacement change command output of the control unit (17) is the reduction phase of the control current of the second solenoid (10). In this case, the displacement change command receiving phase is the displacement increase command receiving phase.

[0173] -If the valve core (4) is in the second position, the activation phase of the corresponding displacement change command output of the control unit (17) is the phase of increasing the control current of the second solenoid (10). In this case, the displacement change command receiving phase is the displacement decrease command receiving phase.

[0174] The method may also include a stage of acquiring the pump temperature via a temperature sensor to detect the pump temperature, a stage of verifying the pump temperature, and an additional stage of generating an alarm signal and / or reducing or stopping the pump speed if the detected temperature is higher than an intervention threshold.

[0175] The present invention also relates to a hydraulic pump (19) wherein the control system is integrated into the structure of the pump, for example at the head of the pump, in the middle position between two control solenoids.

[0176] The present invention also relates to a hydraulic pump (19) equipped with a displacement changing device, wherein the pump (19) includes the displacement changing device of the pump (19), wherein the pump is equipped with a control system (1, 17, 21), the control system (1, 17, 21) includes a displacement changing control device (21), the system is equipped with a servo control device, the servo control device having a cylinder (45), the cylinder (45) including a piston (18), the piston (18) being provided with a connection device to the displacement changing device of the pump (19), the cylinder (45) including the piston (18) 18) A first and second half, separated for conveying pressurized fluid, causing the piston (18) to move in a first direction of motion and a second direction of motion opposite to the first direction, respectively. The system includes a control unit (17), a drive valve (1), and a first solenoid (9) and a second solenoid (10) for controlling the valve (1). The control unit (17) includes a displacement increase input and a displacement decrease input, a first output connected to the first solenoid (9), and a second output connected to the second solenoid (10), wherein the control system (1, 17, 21) is as described above. The control unit (17) may contain a program for processors to implement a control method for the hydraulic pump (19).

[0177] Preferred embodiments of the invention have been described with reference to the accompanying drawings; however, it will be apparent to those skilled in the art that many possible variations, modifications, and alterations will be readily apparent. Therefore, it must be emphasized that the invention is not limited to the above description, but includes all variations, modifications, and alterations according to the appended claims.

[0178] Figure Labels

[0179] The reference numerals used in the attached figures are named as follows:

[0180] 1. Drive valve

[0181] 2. Ontology

[0182] 3. Valve seat

[0183] 4. Main valve core

[0184] 5. Stop the solenoid

[0185] 6. Control valve

[0186] 7. Handle

[0187] 8. Status indicator

[0188] 9. First solenoid

[0189] 10. Second solenoid

[0190] 11. Remote control device

[0191] 12. Emergency button

[0192] 13' Displacement Increase Button

[0193] 13” Displacement Reduction Button

[0194] 14. Charge / Discharge command handle ball head

[0195] 15. Rotation direction command handle ball joint 16. Clearance

[0196] 17. Control Unit

[0197] 18. Piston; 19. Hydraulic pump or variable displacement pump; 20. Control system; 21. Displacement change control device.

[0198] 22. Bypass valve

[0199] 23. First valve

[0200] 24. Second valve

[0201] 25. Second blocking element

[0202] 26. First blocking element

[0203] 27. Inlet pipe 28. Second control pipe

[0204] 29. First control pipeline

[0205] 30. Third discharge pipe

[0206] 31. Fourth discharge pipe

[0207] 32. Fifth discharge pipe

[0208] 33. First discharge pipe

[0209] 34. Second discharge pipe

[0210] 35. First Port

[0211] 36. Second Port

[0212] 37. Springs or elastic elements

[0213] 38. Fulcrum

[0214] 39. Location monitoring device

[0215] 40. Fork

[0216] 41. First Arm

[0217] 42. Second arm

[0218] 43. Displacement increasing solenoid 44. Displacement decreasing solenoid 45. Cylinder

[0219] 46. ​​Connecting elements

[0220] 47. Sell

[0221] 48. Lever

[0222] 49. Board assembly

[0223] 50. Shaft 51. First half-shell

[0224] 52. Second half-shell

[0225] 53. Rotor

[0226] 54. Auxiliary pump or cycloidal pump 55. Distributor plate

[0227] 56. Flange

Claims

1. A control system for a hydraulic pump (19), wherein the hydraulic pump is equipped with a displacement changing device, the system including a displacement changing control device (21), the displacement changing control device being equipped with a servo control device, the cylinder (45) and piston (18) of the servo control device having a connection device connected to the displacement changing device of the hydraulic pump (19), the cylinder (45) including a first half and a second half separated by the piston (18) for delivering pressurized fluid, causing the piston (18) to move in a first direction of motion and a second direction of motion opposite to the first direction of motion, the system including a control unit, a drive valve (1) and a first solenoid (9) and a second solenoid (10) for controlling the valve (1), the control unit including a displacement increase input and a displacement decrease input, a first output connected to the first solenoid (9) and a second output connected to the second solenoid (10), wherein the valve (1) includes a body (2) provided with a conduit. The system is used to alternately deliver fluid in the first or second half of the cylinder (45), the conduit includes an inlet conduit (27), a first control conduit (29), and a second control conduit (28), the valve (1) includes a valve core (4) movable within a valve seat (3) between at least three positions: a neutral position for preventing fluid flow to the cylinder (45), a first position for delivering fluid to the first half of the cylinder (45), and a second position for delivering fluid to the second half of the cylinder (45), the valve core (4) being connected to an elastic element (37) for returning to the neutral position, the first solenoid (9) and the second solenoid (10) being current-operated solenoids, the system including a position detection device (39) of the servo control device for actual position feedback of the servo control device, the control unit including logic for current control of the first output and the second output based on the feedback of the position detection device (39), characterized in that, The position detection device (39) of the servo control device includes a pin (47) connected to the servo control device via a lever (48), such that the movement of the pin (47) corresponds to the movement of the servo control device. An elastic element (37) for returning to a neutral position is disposed between a pair of arms (41, 42) equipped with a fulcrum (38). The valve core (4) is equipped with an engagement element (46) for moving integrally with at least one of the arms (41, 42). The pin (47) is in contact with the pair of arms (41, 42), such that the movement of the pin (47) corresponds to the movement of the servo control device. The reciprocating distance of the pair of arms (41, 42) increases accordingly based on the position of the servo control device. The reciprocating distance of the pin (47) with respect to the pair of arms (41, 42) constitutes the position feedback of the actual position of the servo control device.

2. The control system for a hydraulic pump (19) according to claim 1, characterized in that, The valve (1) includes an inlet pipe (27) for pressurizing fluid, a first control pipe (29) and a second control pipe (28). The first control pipe (29) is in fluid communication with a first half of the cylinder (45), and the second control pipe (28) is in fluid communication with a second half of the cylinder (45). The inlet pipe (27) is located on the body of the valve (1) between the first control pipe (29) and the second control pipe (28).

3. The control system for the hydraulic pump (19) according to claim 2, characterized in that, The first solenoid (9) is positioned opposite to the second solenoid (10) on the valve (1). The first solenoid (9) is configured to apply a pushing force to move the valve core (4) in the first position to connect the fluid communication between the inlet pipe (27) and the first control pipe (29). The second solenoid (10) is configured to apply a reverse pushing force to move the valve core (4) in the second position to connect the fluid communication between the inlet pipe (27) and the second control pipe (28).

4. The control system for the hydraulic pump (19) according to claim 3, characterized in that, The first solenoid (9) independently controls the displacement increase and decrease commands relative to the second solenoid (10) in the first working state of the hydraulic pump, and the second solenoid (10) independently controls the displacement increase and decrease commands relative to the first solenoid (9) in the second working state of the hydraulic pump.

5. The control system for the hydraulic pump (19) according to any one of claims 1-4, characterized in that, The displacement change control device (21) is configured such that the connection device of the displacement change device of the hydraulic pump (19) causes the flow to reverse between the first port (35) and the second port (36) of the hydraulic pump (19) so that the flow passes between the positive displacement corresponding to the first position of the valve core (4) and the negative displacement corresponding to the second position of the valve core (4). In the case of reverse flow between the ports (35, 36), the rotation direction of the hydraulic pump (19) remains the same.

6. The control system for the hydraulic pump (19) according to claim 5, characterized in that, The first operating state of the hydraulic pump corresponds to the positive displacement under the independent control of the first solenoid (9) relative to the second solenoid (10), while the second operating state of the hydraulic pump corresponds to the negative displacement under the independent control of the second solenoid (10) relative to the first solenoid (9).

7. The control system for the hydraulic pump (19) according to any one of claims 3 to 4, characterized in that, The first solenoid (9) is a proportional solenoid used to push the valve core (4) to the first position, which is proportional to the control current of the first output of the control unit.

8. The control system for the hydraulic pump (19) according to any one of claims 3 to 4, characterized in that, The second solenoid (10) is a proportional solenoid used to push the valve core (4) to a second position, which is proportional to the control current of the second output of the control unit.

9. The control system for a hydraulic pump (19) according to claim 8, characterized in that, The valve (1) includes a gap (16) obtained in the space between the valve seat (3) and the valve core (4), the gap (16) communicating with pipes (27, 28, 29), the valve core (4) being provided with a first blocking element (26) and a second blocking element (25) for fluid, the first blocking element (26) and the second blocking element (25) being positioned such that, in the neutral position, the first blocking element (26) blocks the fluid communication between the inlet pipe (27) and the first control pipe (29), while the second blocking element (25) blocks the fluid communication between the inlet pipe (27) and the second control pipe (28), in the first half for conveying fluid to the cylinder (45). In the first position of the second half of the cylinder (45), the first blocking element (26) is positioned such that the inlet pipe (27) and the first control pipe (29) are in fluid communication through the gap (16), while the second blocking element (25) blocks the fluid communication between the inlet pipe (27) and the second control pipe (28).

10. The control system for a hydraulic pump (19) according to claim 9, characterized in that, Each of the first blocking element (26) and the second blocking element (25) consists of a double annular protrusion obtained on the valve core (4), the double annular protrusion forming a double tooth, which closes the corresponding pipe on both sides of the pipe itself when the valve core (4) is in the neutral position, the double annular protrusion allowing flow to the corresponding pipe and blocking flow outside the gap (16) connecting the pipes.

11. The control system for a hydraulic pump (19) according to any one of claims 1-4, characterized in that, The cylinder (45) is a double-acting cylinder with a through rod, wherein the through rod is integral with the piston (18), and the through rod constitutes the connecting device of the displacement changing device of the hydraulic pump (19).

12. The control system for a hydraulic pump (19) according to any one of claims 1-4, characterized in that, The control unit further includes a temperature sensor for detecting the temperature of the hydraulic pump, and is provided with another input for the temperature signal from the temperature sensor of the hydraulic pump and temperature control logic for generating an alarm signal and / or reducing or stopping the speed of the hydraulic pump when the detected temperature is higher than an intervention threshold.

13. The control system for a hydraulic pump (19) according to claim 12, characterized in that, The control unit is made in the form of an electronic card integrated on the body of the hydraulic pump (19). The temperature sensor for temperature detection is mounted on the card and is installed in contact with the hydraulic pump body so that the temperature sensor is in direct contact with the hydraulic pump body itself.

14. The control system for a hydraulic pump (19) according to any one of claims 1-4, characterized in that, The device includes a remote control unit (11) having a communication channel with the control unit. The remote control unit (11) includes at least one operator interface element for controlling displacement increase (13') and an operator interface element for controlling displacement decrease (13"), wherein the operator interface element for controlling displacement increase (13') is connected to the displacement increase input of the control unit through the communication channel, and the operator interface element for controlling displacement decrease (13") is connected to the displacement decrease input of the control unit through the communication channel.

15. The control system for a hydraulic pump (19) according to claim 14, characterized in that, The remote control device (11) includes a status indicator (8) for visualizing status signals and alarm signals, the status indicator (8) being connected to the corresponding signal output of the control unit via the communication channel.

16. The control system for a hydraulic pump (19) according to claim 15, characterized in that, The status indicator (8) is selected between an indicator light and a visualization display for visualizing the signal output of the control unit.

17. The control system for a hydraulic pump (19) according to claim 14, characterized in that, The communication channel can be selected from wireless communication channels, wired communication channels, and serial communication bus communication channels.

18. The control system for the hydraulic pump (19) according to claim 14, characterized in that, The remote control device (11) is made in the form of a touch screen device and is equipped with a program for the processor that constitutes the human-machine interface.

19. A control method for a hydraulic pump (19), wherein the hydraulic pump is equipped with a displacement changing device and a control system, characterized in that, The control system of the hydraulic pump (19) is the control system according to any one of claims 1 to 18, and the method includes the following steps: - An operator receives a displacement change instruction, which is selected between a displacement increase instruction and a displacement decrease instruction; - Activate the corresponding displacement change command input of the control unit, wherein the displacement increase command causes the displacement increase input of the control unit to be activated, and the displacement decrease command causes the displacement decrease input of the control unit to be activated; -The displacement change command is formulated by the control unit; -Activate the corresponding displacement change control output of the control unit; in, The valve (1) includes a body (2) having a conduit for alternately supplying fluid to a first or second half of a cylinder (45), the conduit including an inlet conduit (27), a first control conduit (29), and a second control conduit (28). The valve (1) includes a valve core (4) movable within a valve seat (3) between at least three positions: a neutral position for preventing fluid flow to the cylinder (45), a first position for supplying fluid to the first half of the cylinder (45), and a second position for supplying fluid to the second half of the cylinder (45). The valve core (4) is associated with a return flow mechanism. The system includes a position detection device (39) for a servo control device, for position feedback of the actual position of the servo control device, and the control unit includes logic for current control of a first output and a second output based on the feedback of the position detection device (39). The method includes a phase for controlling the current of the first output and the second output based on the feedback of the position detection device (39) of the servo control device to set the actual position of the servo control device.

20. The control method for the hydraulic pump (19) according to claim 19, characterized in that, - If the valve core (4) is in the neutral position, the activation phase of the corresponding displacement change control output of the control unit is the increase phase of the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement increase command receiving phase. - If the valve core (4) is in the neutral position, the activation phase of the corresponding displacement change control output of the control unit is the phase of increasing the control current of the second solenoid (10). In this case, the displacement change command receiving phase is the displacement decrease command receiving phase.

21. The control method for the hydraulic pump (19) according to any one of claims 19 to 20, characterized in that, -If the valve core (4) is in the first position, the activation phase of the corresponding displacement change control output of the control unit is the increase phase of the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement increase command receiving phase. - If the valve core (4) is in the first position, the activation phase of the corresponding displacement change control output of the control unit is the reduction phase of the control current of the first solenoid (9). In this case, the displacement change command receiving phase is the displacement reduction command receiving phase.

22. The control method for the hydraulic pump (19) according to any one of claims 19 to 20, characterized in that, - If the valve core (4) is in the second position, the activation phase of the corresponding displacement change control output of the control unit is the reduction phase of the control current of the second solenoid (10). In this case, the displacement change command receiving phase is the displacement increase command receiving phase. - If the valve core (4) is in the second position, the activation phase of the corresponding displacement change control output of the control unit is the phase of increasing the control current of the second solenoid (10). In this case, the displacement change command receiving phase is the displacement decrease command receiving phase.

23. The control method for the hydraulic pump (19) according to any one of claims 19 to 20, wherein the control system for the hydraulic pump (19) is the control system for the hydraulic pump (19) according to claim 12, characterized in that, The method further includes a stage of acquiring the temperature of the hydraulic pump through a temperature sensor to detect the temperature of the hydraulic pump, and a stage of verifying the temperature of the hydraulic pump, and an additional stage of generating an alarm signal and / or reducing or stopping the speed of the hydraulic pump if the detected temperature is higher than an intervention threshold.

24. A hydraulic pump (19) having a displacement changing device, wherein the hydraulic pump (19) includes a displacement changing device, the hydraulic pump is provided with a control system, the control system including a control device (21) for changing the displacement, characterized in that, The control system is a control system for a hydraulic pump (19) according to any one of claims 1 to 18, and is integrated into the hydraulic pump structure.

25. The hydraulic pump (19) with a displacement changing device according to claim 24, characterized in that, The control unit includes a program for processor to execute the control method of the hydraulic pump (19) according to any one of claims 19 to 23.

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