WO2024048813A1

WO2024048813A1 - Hydraulic machine

Info

Publication number: WO2024048813A1
Application number: PCT/KR2022/013034
Authority: WO
Inventors: 배상기; 김영훈
Original assignee: 볼보 컨스트럭션 이큅먼트 에이비; 배상기; 김영훈
Priority date: 2022-08-31
Filing date: 2022-08-31
Publication date: 2024-03-07

Abstract

A hydraulic machine comprising: an actuator; a high pressure accumulator; a high pressure line that supplies pressure oil to the actuator and to which the high pressure accumulator is connected; a pump that supplies pressure oil to the high pressure line; a drive unit that drives the pump; and a control unit that controls the pump and the drive unit, wherein the control unit performs control such that, when the pressure in the high pressure line is more than or equal to a preset threshold pressure, the rotational speed of the drive unit is maintained at a preset first rotation speed, and when the pressure in the high pressure line is less than the threshold pressure, the rotational speed of the drive unit is made to be a second rotational speed that is greater than the first rotational speed.

Description

hydraulic machinery

This disclosure relates to hydraulic machines, and more specifically to hydraulic machines having a CPR (Common Pressure Rail) that supplies hydraulic oil to actuators.

Hydraulic machines perform work by obtaining power from the pressure of fluid. Such hydraulic machinery includes, for example, heavy equipment such as excavators. Recently, CPR (Common Pressure Rail) hydraulic machines are known, which are connected to an accumulator and have a high pressure line that supplies hydraulic oil to the actuators.

According to the first aspect of the present disclosure, an actuator, a high-pressure accumulator, a high-pressure line that supplies hydraulic oil to the actuator and to which the high-pressure accumulator is connected, a pump that supplies hydraulic oil to the high-pressure line, and driving the pump a driving unit that controls the pump and the driving unit, and the control unit controls the rotational speed of the driving unit to be maintained at a preset first rotational speed when the pressure in the high pressure line is higher than a preset threshold pressure. and, when the pressure in the high pressure line becomes less than the threshold pressure, the rotational speed of the driving unit is controlled to become a second rotational speed greater than the first rotational speed.

According to the first aspect of the present disclosure, there is an advantage in providing a CPR hydraulic machine with excellent fuel consumption efficiency.

In some examples, the first rotational speed may be a rotational speed within a region representing optimal braking fuel consumption.

In some examples, the second rotational speed may be determined depending on the pressure in the high pressure line.

In some examples, the control unit, if the pressure in the high pressure line is greater than or equal to the threshold pressure, controls the rotation speed of the drive unit to be maintained at the first rotation speed, and also controls the torque of the drive unit to be maintained at the first rotation speed. Control to maintain the torque, and when the pressure in the high pressure line becomes less than the threshold pressure, the rotation speed of the drive unit is controlled to be a second rotation speed greater than the first rotation speed, and the torque of the drive unit is controlled to be a second rotation speed greater than the first rotation speed. It can be controlled to become the second torque.

In some examples, the first rotational speed and the first torque may be a rotational speed and torque within a region representing an optimal braking fuel consumption rate of the hydraulic machine.

In some examples, the second rotational speed is determined depending on the pressure in the high pressure line, and the second torque may be a torque representing the optimal braking fuel consumption rate at the second rotational speed.

In some examples, the control unit integrates the values obtained by multiplying the difference between the second torque and the current torque (T _req -T _cur ) by the gain value and dividing the values by the inlet and outlet pressure difference values of the pump. The volume of the pump can be controlled depending on the value.

In some examples, the controller may increase the volume of the pump when the integral value increases and may decrease the volume of the pump when the integral value decreases.

In some examples, the controller may prevent the integral value from increasing any further when the integral value reaches a preset maximum value.

In some examples, the control unit calculates the torque of the pump from the pressure and volume of the pump, and rotates the drive unit at a rotation speed greater than the second rotation speed if the instantaneous rate of change of the torque of the pump is positive, If the instantaneous rate of change of the torque of the pump is negative, the driving unit may be rotated at a rotational speed smaller than the second rotational speed.

In some examples, the control unit calculates the torque of the pump from the pressure and volume of the pump, and if the instantaneous rate of change of the torque of the pump is positive, 'second rotation speed + D*dT' greater than the second rotation speed. /dt', and if the instantaneous rate of change of the torque of the pump is negative, the driving part is rotated at 'second rotation speed + D*dT/dt', which is smaller than the second rotation speed, where D is The gain value, dT/dt, may be the instantaneous rate of change of the torque of the pump.

The foregoing aspects, the appended claims and the examples disclosed herein above or below may be appropriately combined with each other, as will be apparent to those skilled in the art.

Additional features and advantages are disclosed in the following description, claims, and drawings, and additional features and advantages will to some extent be readily apparent to a person of ordinary skill in the art or disclosed herein. It can be understood by realizing water. Also disclosed herein are control units, computer-readable media, and computer program products related to the technical advantages described above.

Aspects of the disclosure, cited by way of example, are described in detail below with reference to the accompanying drawings.

1 is a diagram showing a schematic configuration of a hydraulic machine according to an example of the present disclosure.

Figure 2 is a brake-specific fuel consumption (BSFC) map of a hydraulic machine according to an example of the present disclosure.

Figure 3 is a block diagram schematically showing the configuration of a torque controller of a driving part of a control part of a hydraulic machine according to an example of the present disclosure.

Figure 4 is a graph showing how the drive unit torque controller adjusts the volume of the pump to control the torque of the drive unit.

Figure 5 is a block diagram schematically showing the configuration of a rotational speed compensator of a driving unit of a hydraulic machine control unit according to an example of the present disclosure.

Figure 6 is a graph showing how the drive unit rotation speed compensator performs compensation.

Figure 7 is a block diagram schematically showing the overall configuration of a control unit of a hydraulic machine according to an example of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS Aspects of the present disclosure cited by way of example will be described in detail below with reference to the accompanying drawings. The aspects described below present the necessary information to enable a person skilled in the art to practice the present disclosure.

Hydraulic machines of the present disclosure typically relate to heavy equipment such as excavators, but are not limited thereto and may include any machine that performs work by obtaining power from the pressure of a fluid.

The hydraulic machine may include at least one actuator, a high pressure accumulator 310, a high pressure line 315, a pump 120, a driving unit 110, and a control unit 600. Additionally, in some examples, the hydraulic machine may include a low pressure accumulator 320 and a low pressure line 325. Additionally, in some examples, the hydraulic machine may include a tank. Additionally, in some examples, the hydraulic machine may include a valve 210 that allows or blocks the flow of fluid from the pump 120 to the high pressure line 315. Additionally, in some instances, the hydraulic machine may include a valve 210 that allows or blocks the flow of fluid from the low pressure line 325 to the tank. Additionally, in some examples, the hydraulic machine may include a valve (not shown) that allows or blocks the flow of fluid from the high pressure line 315 to the actuator, and a valve (not shown) that allows or blocks the flow of fluid from the actuator to the low pressure line 325. It may include a blocking valve (not shown).

The actuator is connected to the high pressure line 315, receives high pressure hydraulic oil from the high pressure line 315, and uses power from the pressure of the hydraulic oil to enable the hydraulic machine to perform work. Additionally, the actuator may be connected to the low-pressure line 325 and discharge operating oil into the low-pressure line 325. The actuator may include, for example, a boom actuator 410, an arm actuator 420, a bucket actuator 430, a swing actuator 440, and

travel actuators

451 and 453. Boom actuator 410, arm actuator 420, and bucket actuator 430 may be hydraulic cylinders. The swing actuator 440 and

travel actuators

451 and 453 may be hydraulic motors. The actuator may include an inlet port through which the actuator is connected to the high pressure line 315, and an outlet port through which the actuator is connected to the low pressure line 325.

A high pressure accumulator 310 is connected to the high pressure line 315. Additionally, as described above, the high pressure line 315 may be connected to the actuator to supply pressure oil to the actuator.

A low-pressure accumulator 320 is connected to the low-pressure line 325. Additionally, as described above, the low pressure line 325 is connected to the actuator so that hydraulic oil can be discharged from the actuator through the low pressure line 325.

The pump 120 pressurizes the hydraulic oil to produce pressure oil and sends the pressure oil to the high pressure accumulator 310 and the actuator through the high pressure line 315. The pump 120 may be a variable capacity pump whose volume (volume of hydraulic oil discharged per rotation) is variable. The volume of the pump 120 may be controlled by the control unit 600. In some examples, the pump 120 has a swash plate, and the control unit 600 sends a signal to the pump 120 to change the inclination angle of the swash plate of the pump 120 to control the volume of the pump 120. You can. The hydraulic machine may include at least one pump 120.

The driving unit 110 is a component that drives the pump 120 and may typically include an engine. However, the present disclosure is not limited to this, and may be another type of driving unit capable of driving the pump 120, such as an electric motor.

The control unit 600 can control each component of the hydraulic machine, particularly the volume of the pump 120 and the rotation speed of the drive unit 110. The control unit 600 may include an electronic control unit that receives commands input through an operator interface and/or reads values from various sensors, interprets the commands and/or data, and then generates and outputs a control signal. You can.

The tank may provide hydraulic oil to the hydraulic pump 120 and store hydraulic oil returned from the actuator through the low pressure line 325.

In a typical hydraulic machine without an accumulator, the rotational speed of the drive unit 110 and the volume of the pump 120 are variable in order to maintain performance. On the other hand, in the CPR hydraulic machine according to an example of the present disclosure, in a normal state in which the actuator consumes a flow rate less than the maximum flow rate that the pump 120 can supply, the rotation speed of the drive unit 110 is the preset first rotation. The speed can be controlled to be maintained. Additionally, at this time, the torque of the driving unit 110 may be controlled to be maintained at a preset first torque.

The first rotational speed and first torque may be the rotational speed and torque within a region representing the optimal braking fuel consumption rate of the hydraulic machine, the so-called sweet spot. Low brake fuel consumption means that the same power can be achieved with relatively less fuel consumption.

In some examples, the first rotation speed and first torque may be provided as preset values. Referring to FIG. 2, the first rotation speed may be preset to, for example, 1400 rpm and the first torque may be preset to, for example, 700 Nm, and in this setting, the pump 120 operates at a maximum flow rate that the pump 120 can supply, for example, 220 lpm. Can be supplied to the high pressure line 315.

The rotation speed of the driving unit 110 can be directly controlled by a control signal. However, the torque of the driving unit 110 (assuming that most of the torque is consumed by the pump 120) is determined by the volume of the pump 120 and the inlet and outlet pressure difference of the pump 120 (i.e., the outlet of the pump 120). Pressure - controlled depending on the inlet pressure of the pump 120). When the drive unit 110 is operated at a rotation speed of 1400 rpm, the pump 120 may be controlled to have a maximum volume, for example, in accordance with a torque of 700 Nm. However, these settings may have the following limitations:

If the actuator consumes a flow rate that exceeds the maximum flow rate that the pump 120 can supply, the pressure in the high pressure line 315 drops rapidly and the performance of the actuator deteriorates. Therefore, in order to recharge the high-pressure accumulator 310 and send the required flow rate to the actuator, the supply flow rate of the pump 120 supplied to the high-pressure line 315 must be increased. However, fixed rotation speed and torque cannot cope with this situation.

Therefore, in the hydraulic machine according to an example of the present disclosure, in the normal state in which the actuator consumes a flow rate less than the maximum flow rate that the pump 120 can supply, as described above, the control unit 600 controls the driving unit 110. The rotation speed may be controlled to be maintained at the first rotation speed, and the torque of the drive unit 110 may be controlled to be maintained at the first torque. However, if the actuator consumes a flow rate that exceeds the maximum flow rate that the pump 120 can supply, the control unit 600 controls the drive unit 110 so that the pump 120 can supply more flow rate to the high pressure line 315. The rotation speed can be controlled to be a second rotation speed that is greater than the first rotation speed.

If the actuator consumes a flow rate that exceeds the maximum flow rate that the pump 120 can supply, the pressure in the high pressure line 315 drops, so it is important to determine whether the actuator consumes a flow rate that exceeds the maximum flow rate that the pump 120 can supply. This can be known by measuring the pressure in the high pressure line 315. Therefore, if the pressure in the high pressure line 315 is higher than the preset threshold pressure, the control unit 600 controls the rotational speed of the driver 110 to be maintained at the preset first rotational speed, and the pressure in the high pressure line 315 When the pressure falls below this threshold, the rotational speed of the drive unit 110 can be controlled to become a second rotational speed that is greater than the first rotational speed. Here, the second rotation speed may be determined according to the pressure in the high pressure line 315. In some examples, a lookup table in which the value of the pressure in the high pressure line 315 and the value of the second rotational speed are mapped may be stored in advance in the memory, and the second rotational speed may be determined by referring to this lookup-table. there is.

If the rotation speed of the drive unit 110 is controlled to be a second rotation speed that is greater than the first rotation speed, the rotation speed of the drive unit 110 deviates from the above-described sweet spot. Therefore, the torque of the driving unit 110 must be newly set, and in the hydraulic machine according to an example of the present disclosure, when the actuator consumes a flow rate exceeding the maximum flow rate that the pump 120 can supply, that is, the high pressure line 315 ) When the pressure within the unit becomes less than the threshold pressure, the torque of the drive unit 110 can be controlled to become the second torque. The second torque is a torque representing optimal fuel consumption efficiency at the second rotation speed, and the points of the second rotation speed and second torque form a new spot line in the BSFC map, as shown in FIG. 2. In some examples, a lookup-table in which the value of the second rotational speed and the value of the second torque are mapped (or, since the second rotational speed is determined depending on the pressure in the high pressure line 315, the pressure in the high pressure line 315 A lookup-table in which the value of and the value of the second torque are mapped may be stored in advance in the memory, and the second torque may be determined by referring to this lookup-table.

Referring to Figure 2, for example,

(1) When the safety lever is lowered, the drive unit 110 can maintain an idle state at 800 rpm.

(2) When the driver raises the safety lever but does not operate the actuator operation lever (not shown), the rotation speed of the drive unit 110 is maintained at 1400 rpm and the torque is maintained at the minimum torque.

(3) With the safety lever raised, the driver operates the actuator operation lever, and when the flow rate consumed by the actuator is less than the flow rate that the pump 120 can provide at the maximum volume at 1400 rpm, the rotation speed is maintained at 1400 rpm and the drive unit ( The torque of 110) repeatedly rises and falls within the sweet spot. In this state, hydraulic machines operate at maximum efficiency.

(4) If the driver operates the actuator operation lever with the safety lever raised and the actuator consumes more than the maximum flow rate of the pump 120, the pressure in the high pressure line 315 increases because the flow rate of the accumulator is additionally used. It falls. In this case, the rotational speed of the driving unit 110 is controlled to increase to the second rotational speed according to the amount of pressure drop in the high pressure line 315, thereby increasing the discharge flow rate of the pump 120. In addition, the second torque corresponding to the second rotation speed on the sweet line is controlled to become the torque of the driving unit 110. Referring to FIG. 2, the sweet line starts at, for example, 1400 rpm and 700 Nm, and the second rotation speed increases and the second torque slightly decreases along the sweet line.

Figure 3 is a block diagram schematically showing the configuration of the driving part torque controller of the control part of the hydraulic machine according to an example of the present disclosure, and Figure 4 shows the driving part torque controller of the pump 120 to control the torque of the driving part 110. This is a graph showing volume control.

Referring to FIG. 2 , we have previously seen that in some examples, the control unit 600 can control the torque of the drive unit 110 to become the second torque (T _req ) on the sweet line. However, engine torque is the sum of the torque of the main pump, the torque of other small pumps, and other torques. Although the main pump occupies a large portion of the torque of the drive unit 110, the torque of the drive unit 110 may not be maintained at the second torque (T _req ) due to other torques and may deviate. Additionally, it is difficult to predict how much the torque of the driving unit 110 will deviate.

Accordingly, in some examples, the control unit 600 may perform feedback control so that the current torque (T _cur ) of the driving unit 110 is equal to the second torque (T _req ).

Referring to FIG. 3 , in some examples, the control unit 600 may multiply the difference between the second torque (T _req ) and the current torque (T _cur ) (T _req - T _cur ) by a gain value. The volume (V _com ) of the pump 120 can be adjusted according to the integral value obtained by dividing the values by the inlet and outlet pressure difference values of the pump (P _pump ). The controller 600 may increase the volume of the pump 120 when the integral value increases and may decrease the volume of the pump 120 when the integral value decreases. for example,

Volume change [cc/rev] = 20 * π * Torque difference [Nm] / Pump inlet/outlet pressure difference [bar] * Gain

It can be given as . Here, π represents the pi.

Meanwhile, the volume (V _com ) of the pump 120 has a maximum value that cannot be further increased in terms of hardware. Therefore, anti-windup functionality can be added to the integrator. The anti-windup function prevents the integral value from increasing further when the integral value reaches a preset maximum value. As long as the integral value is within the maximum value, the anti-windup function does not work. If you do not do so, the volume (V _com ) of the pump 120 has reached the maximum value, but the integral value continues to increase, and even if you try to reduce the volume (V _com ) of the pump 120, the maximum value of the integral value This is because the volume (V _com ) of the pump 120 cannot be reduced until the amount exceeding is eliminated.

In some examples, the hydraulic machine may include an engine sensor 520 to determine engine torque.

FIG. 5 is a block diagram schematically showing the configuration of a drive unit rotation speed compensator of a control unit of a hydraulic machine according to an example of the present disclosure, and FIG. 6 is a graph showing the drive unit rotation speed compensator performing compensation.

When a high torque is applied to the drive unit 110, the rotation speed of the drive unit 110 decreases. Therefore, there is a need to solve this phenomenon. As a solution, you can first consider compensating for the rotation speed drop using the actual rotation speed value. However, this may cause fluctuations in rotational speed and, as a result, reduce fuel consumption efficiency. Therefore, another solution is needed.

The main cause of the decrease in rotation speed of the drive unit 110 is the rate of change of the torque of the drive unit 110. The main part of the torque of the drive unit 110 is related to the torque of the main pump calculated by the following equation.

, where V is volumetric displacement

Accordingly, in the hydraulic machine according to an example of the present disclosure, the control unit 600 may compensate for the rotational speed of the driving unit 110 using the instantaneous rate of change of the torque of the pump 120. For example, in some examples, the control unit 600 calculates the torque of the pump 120 from the inlet and outlet pressure difference (Ppump) and the volume (Vcom) of the pump 120, and the instantaneous rate of change of the torque of the pump 120 is If positive, the drive unit 110 is rotated at a rotation speed (ω _com ) greater than the second rotation speed (ω req ), and if the instantaneous rate of change of torque of _the pump 120 is negative, the rotation is less than the second rotation speed (ω _req ). The driving unit 110 can be rotated at a speed (ω _com ). If the instantaneous rate of change of the torque of the pump 120 is positive, a drop in rotational speed is expected, so the drop in rotational speed is compensated by rotating the drive unit 110 at a rotational speed (ω _com ) greater than the second rotational speed (ω _req ). By doing so, the rotational speed of the pump 120 is ultimately controlled to be maintained at the second rotational speed (ω _req ).

In some examples, the control unit 600, if the instantaneous rate of change of the torque of the pump 120 is positive, 'second rotation speed (ω _req ) + D*dT/dt' greater than the second rotation speed (ω _req ). The driving unit 110 is rotated, and if the instantaneous rate of change of the torque of the pump 120 is negative, the driving unit 110 is rotated at a 'second rotational speed (ω _req ) + D*dT/dt' that is smaller than the second rotational speed (ω _req ). ) can be rotated. Here, D is the gain value, and dT/dt is the instantaneous rate of change of the torque of the pump 120.

Referring to FIG. 5, in some examples, the control unit 600 multiplies the torque value of the pump 120 obtained by calculation by the gain value, and if the instantaneous rate of change of the product is positive, it is faster than the second rotation speed (ω _req ). The driving unit 110 is rotated at a large second rotation speed (ω _req ) + D*dT/dt, and if negative, the second rotation speed (ω _req ) + D* is smaller than the second rotation speed (ω _req ). The driving unit 110 can be rotated by 'dT/dt'.

According to one example, the control of the rotational speed (ω _com ) of the driving unit 110 and the volume (V _com ) of the pump 120 will be sequentially examined as follows.

Process 1) Using the pressure sensor 510, the pressure in the high pressure line 315 is measured, and the rotation speed determination unit 630 determines the rotation speed of the driving unit 110. As described above with reference to FIG. 2, when the pressure in the high pressure line 315 is greater than the threshold pressure, the rotational speed is maintained at the preset first rotational speed, and when the pressure in the high pressure line 315 is less than the threshold pressure, The rotation speed increases to the second rotation speed (ω _req ).

Process 2) Receives a second rotational speed value (ω _req ) from process 1, and the torque determination unit 640 generates a second torque value (T _req ) corresponding to the second rotational speed (ω _req ) on the sweet line ( That is, the second torque value (T _req ) representing the optimal fuel consumption efficiency at the second rotation speed is found.

Process 3) The second torque value (T _req ) is received from process 2, and the current torque value (T _cur ) of the driving unit 110 is read using the engine sensor 520 . As shown in FIG. 3 , the drive unit torque controller 610 transmits a pump volume command (V _com ) to the pump 120 to control the volume of the pump 120 .

Process 4) The drive unit rotation speed compensator 620 receives the pump volume command value (V _com ) for controlling the volume of the pump 120 from Process 3 and also receives the second rotation speed value (ω _req ) from Process 1. Receive. And using the pump volume command value (V _com ) and the second rotation speed value (ω _req ), how much value should be added or subtracted from the second rotation speed (ω _req ) to prevent the rotation speed droop phenomenon. A rotation speed command (ω _com ) is transmitted to the drive unit 110 .

The terminology used herein is for the purpose of describing certain aspects only and is not intended to limit the disclosure. Unless the context clearly indicates otherwise, plural forms may be included even if written in singular form. Additionally, the term “and/or” includes any and all combinations of one or more of the associated listed items. The term “comprising” specifies the presence of stated features, integers, steps, operations, elements and/or components, but also includes one or more other features, integers, steps, operations, elements, It does not exclude the presence or addition of components and/or groups thereof.

Comparative terms such as “below,” “above,” “above,” “further below,” “horizontal,” or “vertical” are used herein to describe the relationship of any element shown in the figures to another element. You can. These terms and the foregoing may include other orientations of the device as well as the orientation shown in the figures. When an element is said to be connected or combined with another element, this may include not only a direct connection, but also other intervening elements. On the other hand, when an element is said to be directly connected or coupled to another element, this means that no intermediate elements exist.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. Terms used herein should be construed to have meanings consistent with their meanings in the context of this specification and related art, and, unless explicitly defined herein, should not be interpreted in an idealized or overly formal sense. will be.

The present disclosure is not limited to the aspects shown in the foregoing and drawings, but rather, those skilled in the art will understand that various changes and modifications may be made within the scope of the present disclosure and the appended claims. shall. Many aspects are disclosed in the drawings and specification for purposes of illustration rather than limitation, and the scope of the inventive concept is set forth in the claims that follow.

Claims

an actuator,

A high pressure accumulator,

A high pressure line that supplies pressure oil to the actuator and to which the high pressure accumulator is connected,

A pump that supplies pressure oil to the high pressure line,

A driving unit that drives the pump,

It includes a control unit that controls the pump and the driving unit,

The control unit,

If the pressure in the high pressure line is higher than the preset threshold pressure, the rotational speed of the driving unit is controlled to be maintained at the preset first rotational speed,

When the pressure in the high pressure line becomes less than the threshold pressure, the rotation speed of the driving unit is controlled to be a second rotation speed greater than the first rotation speed,

Hydraulic machinery.
According to claim 1,

The first rotational speed is a rotational speed within a region representing the optimal braking fuel consumption rate,

Hydraulic machinery.
According to claim 1,

The second rotation speed is determined depending on the pressure in the high pressure line,

Hydraulic machinery.
According to claim 1,

The control unit,

If the pressure in the high pressure line is equal to or higher than the threshold pressure, the rotational speed of the driving unit is controlled to be maintained at the first rotational speed, and the torque of the driving unit is controlled to be maintained at a preset first torque,

When the pressure in the high pressure line is less than the threshold pressure, the rotation speed of the drive unit is controlled to be a second rotation speed greater than the first rotation speed, and the torque of the drive unit is controlled to be a second torque. ,

Hydraulic machinery.
According to clause 4,

The first rotational speed and the first torque are the rotational speed and torque within a region representing the optimal braking fuel consumption rate of the hydraulic machine,

Hydraulic machinery.
According to clause 4,

The second rotation speed is determined according to the pressure in the high pressure line,

The second torque is a torque representing the optimal braking fuel consumption rate at the second rotation speed,

Hydraulic machinery.
According to clause 4,

The control unit operates the pump according to an integral value obtained by dividing the difference between the second torque and the current torque (T req -T cur ) by the gain value divided by the inlet and outlet pressure difference values of the pump. controlling the volume of,

Hydraulic machinery.
According to clause 7,

The control unit,

When the integral value increases, the volume of the pump increases,

When the integral value decreases, the volume of the pump is reduced,

Hydraulic machinery.
According to clause 8,

The control unit prevents the integral value from increasing further when the integral value reaches a preset maximum value.

Hydraulic machinery.
According to claim 1,

The control unit,

Calculate the torque of the pump from the pressure and volume of the pump,

If the instantaneous rate of change of the torque of the pump is positive, the driving unit is rotated at a rotational speed greater than the second rotational speed, and if the instantaneous rate of change of the torque of the pump is negative, the driving unit is rotated at a rotational speed less than the second rotational speed. Shiki,

Hydraulic machinery.
According to claim 10,

The control unit,

Calculate the torque of the pump from the pressure and volume of the pump,

If the instantaneous rate of change of the torque of the pump is positive, the driving unit is rotated at a 'second rotation speed + D*dT/dt' greater than the second rotation speed, and if the instantaneous rate of change of the torque of the pump is negative, the second rotation is performed. Rotate the driving unit at a 'second rotation speed + D*dT/dt' that is smaller than the speed,

Here, D is the gain value, and dT/dt is the instantaneous rate of change of the torque of the pump,

Hydraulic machinery.