A piston accumulator and pressure control method

Abstract

The present invention discloses a piston accumulator and a pressure control method, belonging to the technical field of accumulators. The piston accumulator comprises a cylinder barrel that can form a closed cavity, a piston assembly and a driving assembly for driving the piston assembly to move. The piston assembly comprises a piston and a piston rod fixedly connected to the piston. The piston is placed inside the cylinder barrel and divides the cavity inside the cylinder barrel into an air cavity and an oil cavity. The air cavity is connected to an air source, and the oil cavity is connected to an oil source. The piston rod passes through and extends out of the air cavity, and one end extending out of the air cavity is transmission-connected to the driving assembly and can drive the piston to move left and right under the action of the pressure difference between the driving assembly and the air cavity and the oil cavity. The driving component makes up for the gap between the oil pressure and the linear change when the piston is only under the action of the pressure difference, thereby solving the problem of nonlinear change of the oil pressure in the accumulator.

Description

Technical Field

[0001] The present invention relates to the technical field of accumulators, and in particular to a piston accumulator and a pressure control method. Background Art

[0002] Piston accumulators play a role in pressure stabilization and energy recovery and reuse in hydraulic systems. Their operating principle is as follows: a piston separates the cylinder into an air chamber and an oil chamber, with the oil chamber connected to the hydraulic line. When the hydraulic system experiences pressure fluctuations due to load during operation, the accumulator's high-pressure gas acts on the oil chamber through the piston, effectively reducing the pressure fluctuation. When accumulators are used for energy recovery and reuse in hydraulic systems, these hydraulic systems are often liquid-gas balance systems, typically used in mobile construction machinery. The accumulator pressure is used to balance the weight of the working device. When the working device descends, the accumulator recovers energy, and when it ascends, the accumulator releases stored energy. A common problem encountered when using accumulators in this system is the nonlinear variation of the accumulator oil pressure. Currently, most solutions to this problem involve using valve control to reduce the impact of nonlinear variations in the accumulator oil pressure on system operation and control. However, the fundamental issue of this nonlinear variation remains unresolved.

[0003] Therefore, how to provide a piston accumulator and a pressure control method to solve the nonlinear change of the oil pressure of the existing accumulator has become a technical problem that needs to be solved urgently. Summary of the Invention

[0004] The purpose of the present invention is to address the defects and shortcomings of the prior art and provide a piston accumulator and a pressure control method to solve the problem of nonlinear changes in the oil pressure of the accumulator.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides a piston accumulator, comprising a cylinder barrel capable of forming a closed cavity, a piston assembly, and a drive assembly for driving the piston assembly to move. The piston assembly comprises a piston and a piston rod fixedly connected to the piston. The piston is disposed inside the cylinder barrel and divides the cavity inside the cylinder barrel into an air cavity and an oil cavity. The air cavity is connected to an air source, and the oil cavity is connected to an oil source. The piston rod penetrates and extends out of the air cavity, and one end extending out of the air cavity is transmission-connected to the drive assembly, and can drive the piston to move left and right under the action of the pressure difference between the drive assembly and the air cavity and the oil cavity.

[0007] Preferably, the drive assembly includes a ball screw, a motor and a power supply for powering the motor. The interior of the piston rod is provided with an internal thread adapted to the ball screw, and the end of the ball screw away from the piston rod is transmission-connected to the motor.

[0008] Preferably, the electric machine can be used as both a motor and a generator.

[0009] Preferably, the power supply includes an inverter and a DC power supply, and the DC power supply is connected to the motor through the inverter.

[0010] Preferably, the DC power supply is a battery or a supercapacitor.

[0011] Preferably, it also includes a control unit, a first pressure sensor for measuring the air chamber pressure, and a second pressure sensor for measuring the oil chamber pressure. The first pressure sensor, the second pressure sensor, and the inverter are respectively connected to the control unit for signals.

[0012] Preferably, the control unit includes an A / D converter, an adder and a pressure difference / torque interpolation table which are connected in sequence, the A / D converter is respectively connected to the first pressure sensor and the second pressure sensor signals, and the pressure difference / torque interpolation table is connected to the inverter signal.

[0013] Preferably, the cylinder barrel has an air intake end cover and an oil intake end cover, and the air intake end cover and the oil intake end cover are respectively detachably connected to the cylinder barrel.

[0014] Preferably, the parts where the air intake end cover and the oil intake end cover contact the cylinder barrel, the parts where the air intake end cover contact the piston rod, and the parts where the piston contact the cylinder barrel are all provided with sealing components.

[0015] The present invention also provides a pressure control method for a piston accumulator, which uses the piston accumulator and includes the following contents:

[0016] S1. The first and second pressure sensors collect pressure information from the air and oil chambers, respectively. The collected pressure information is converted to digital values ​​by an A / D converter, and the difference between the two values ​​is calculated by an adder, denoted as δ1.

[0017] S2. The control unit is provided with a target pressure digital value, and the difference 2 between the target pressure digital value and δ1 is calculated by the adder, recorded as δ2;

[0018] S3. The difference δ2 is connected to the pressure difference / torque interpolation table, and the corresponding voltage of the torque required when the output motor is used as a motor is output. The inverter is controlled to further control the torque of the motor when used as a motor, thereby achieving a linear change in the oil pressure during the movement of the piston.

[0019] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0020] 1. The present invention achieves left-right movement of the piston by connecting the piston rod to the drive assembly and moving it left-right under the action of the drive assembly and the pressure difference between the air chamber and the oil chamber. Compared with the prior art method of achieving left-right movement of the piston only by the pressure difference between the air chamber and the oil chamber, the present invention solves the problem of nonlinear change of the accumulator oil pressure by setting a fixed connection between the piston rod and the piston and moving it under the combined action of the drive assembly and the pressure difference.

[0021] Other technical solutions of the present invention have the following beneficial effects compared with the prior art:

[0022] 2. The present invention can more accurately regulate the torque of the motor by providing a control component, a first pressure sensor and a second pressure sensor, so that the oil pressure of the accumulator can achieve more accurate linear changes, thereby improving the operating effect of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the main cross-sectional structure of a piston accumulator disclosed in a specific embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the operating principle of a control unit of a piston accumulator disclosed in a specific embodiment of the present invention.

[0026] Among them, 1. Inverter; 2. Motor; 3. Ball screw; 4. Sealing component; 5. Cylinder; 6. Oil inlet cover; 7. Oil chamber; 8. Piston; 9. Air chamber; 10. Air inlet cover; 11. Piston rod; 12. Power supply; 13. Control unit. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1As shown, the present invention provides a piston accumulator, comprising a cylinder 5 capable of forming a closed cavity, a piston assembly, and a drive assembly for driving the piston assembly to move. The piston assembly includes a piston 8 and a piston rod 11 fixedly connected to the piston 8. The piston 8 is positioned within the cylinder 5 and divides the cavity within the cylinder 5 into an air chamber 9 and an oil chamber 7. The air chamber 9 is connected to an air source, and the oil chamber 7 is connected to an oil source. The piston rod 11 extends through and extends from the air chamber 9. The end extending from the air chamber 9 is transmission-connected to the drive assembly and can drive the piston 8 to move left and right under the action of the drive assembly and the pressure differential between the air chamber 9 and the oil chamber 7. The movement process of the piston 8 is described using the air chamber 9 on the left and the oil chamber 7 on the right as an example. When the pressure in the air chamber 9 is lower than the pressure in the oil chamber 7, the piston 8 moves to the left under the action of the pressure difference. When the pressure in the air chamber 9 is higher than the pressure in the oil chamber 7 and the piston 8 needs to move to the right, the piston 8 moves to the right under the action of the drive component and the pressure difference. The drive component makes up for the gap between the oil pressure when the piston 8 is only under the action of the pressure difference and the linear change, thereby solving the problem of nonlinear change of the oil pressure in the accumulator.

[0030] The drive assembly can be a gear rack structure, an electric push rod structure, etc. By adjusting the motion parameters of the gear rack structure or the electric push rod, the gap between the oil pressure and the linear change when the piston 8 is only under the action of the pressure difference is compensated. In one embodiment, the drive assembly includes a ball screw 3, a motor 2, and a power supply 12 for powering the motor 2. The interior of the piston rod 11 is provided with an internal thread compatible with the ball screw 3. The ball screw 3 extends into the interior of the piston rod 11, and the end of the ball screw 3 away from the piston rod 11 is connected to the motor 2 in a transmission manner. The motor 2 drives the ball screw 3 to rotate, thereby pushing the piston rod 11 and the piston 8 to move linearly. By adjusting the operating parameters of the motor 2, the gap between the oil pressure and the linear change when the piston 8 is only under the action of the pressure difference is compensated. The motor 2 used in this embodiment can be used as both an electric motor and a generator, such as the motors used in existing new energy vehicles. When the pressure in the oil chamber 7 is greater than the pressure in the air chamber 9 and the piston 8 moves to the left, the motor 2 acts as a generator. At this time, the piston rod 11 drives the ball screw 3 to rotate and drives the generator to generate electricity, and the electricity is stored in the power supply 12. Among them, the internal thread of the piston rod 11 does not experience thread self-locking during the movement, to ensure that the rotation of the ball screw 3 can both drive the piston rod 11 to move, and the movement of the piston rod 11 can drive the ball screw 3 to rotate; when the pressure in the oil chamber 7 is less than the pressure in the air chamber 9 and the piston 8 needs to move to the right, the motor 2 acts as an electric motor to drive the ball screw 3 to rotate and assist and adjust the piston 8 to the right to achieve a linear change in oil pressure. The power supply 12 used in this embodiment includes an inverter 1 and a DC power supply, and the DC power supply is connected to the motor 2 through the inverter 1. The DC power supply can be any one of a battery and a supercapacitor.

[0031] To achieve precise control, the piston accumulator of the present invention further includes a control unit 13, a first pressure sensor for measuring the pressure in the air chamber 9, and a second pressure sensor for measuring the pressure in the oil chamber 7. The first and second pressure sensors and the inverter 1 are each signal-connected to the control unit 13. The control unit 13 adjusts the operating parameters of the motor 2 based on the pressure data measured by the first and second pressure sensors.

[0032] refer to Figure 2 The control unit 13 includes an A / D converter, an adder, and a pressure difference / torque interpolation table, which are sequentially connected. The A / D converter is signal-connected to the first pressure sensor and the second pressure sensor, respectively, and the pressure difference / torque interpolation table is signal-connected to the inverter 1. The adder used here is a device that can be configured to calculate the difference.

[0033] refer to Figure 1 The cylinder barrel 5 has an air inlet cover 10 and an oil inlet cover 6, each of which is detachably connected to the cylinder barrel 5 to facilitate replacement of damaged components. Seals 4 are provided at the points where the air inlet cover 10 contacts the cylinder barrel 5, where the oil inlet cover 6 contacts the cylinder barrel 5, where the air inlet cover 10 contacts the piston rod 11, and where the piston 8 contacts the cylinder barrel 5 to prevent leakage.

[0034] Continue to refer Figure 2 The present invention also provides a pressure control method for a piston accumulator, which uses the above-mentioned piston accumulator and includes the following contents:

[0035] S1. The first pressure sensor and the second pressure sensor respectively collect pressure information of the air chamber 9 and the oil chamber 7. The collected pressure information is converted into a digital value by an A / D converter, and the difference between the two is calculated by an adder, denoted as δ1;

[0036] S2. The control unit 13 is provided with a target pressure digital quantity, and the difference between the target pressure digital quantity and δ1 is calculated by the adder 2, recorded as δ2;

[0037] S3. The difference δ2 is connected to the pressure difference / torque interpolation table, and the corresponding voltage of the torque required when the output motor 2 is used as a motor is output. The inverter 1 is controlled to further control the torque of the motor 2 when used as a motor, thereby achieving a linear change in the oil pressure during the movement of the piston 8.

[0038] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all perspectives, the embodiments should be regarded as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description. It is intended that all changes that fall within the meaning and range of equivalents of the claims be included in the present invention, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

Claims

1. A piston accumulator, characterized in that: The invention comprises a cylinder barrel that can form a closed cavity, a piston assembly, and a drive assembly for driving the piston assembly to move, wherein the piston assembly comprises a piston and a piston rod fixedly connected to the piston, the piston being placed inside the cylinder barrel and dividing the cavity inside the cylinder barrel into an air cavity and an oil cavity, the air cavity being connected to an air source, the oil cavity being connected to an oil source, the piston rod passing through and extending out of the air cavity, and one end extending out of the air cavity being transmission-connected to the drive assembly, and being capable of driving the piston to move left and right under the action of the drive assembly and the pressure difference between the air cavity and the oil cavity; When the pressure in the air chamber is lower than that in the oil chamber, the piston moves to the left under the action of the pressure difference. When the pressure in the air chamber is higher than that in the oil chamber and the piston needs to move to the right, the piston moves to the right under the action of the drive assembly and the pressure difference. The drive assembly makes up for the gap between the oil pressure and the linear change when the piston is only under the action of the pressure difference, thus solving the problem of nonlinear change of the oil pressure in the accumulator.

2. The piston accumulator according to claim 1, characterized in that: The driving assembly includes a ball screw, a motor and a power supply for powering the motor. The interior of the piston rod is provided with an internal thread adapted to the ball screw. The end of the ball screw away from the piston rod is transmission-connected to the motor.

3. The piston accumulator according to claim 2, characterized in that: The electric machine can be used as both a motor and a generator.

4. The piston accumulator according to claim 3, characterized in that: The power supply includes an inverter and a DC power supply, and the DC power supply is connected to the motor through the inverter.

5. The piston accumulator according to claim 4, characterized in that: The DC power supply is a battery or a super capacitor.

6. The piston accumulator according to claim 4, characterized in that: It also includes a control unit, a first pressure sensor for measuring the air cavity pressure, and a second pressure sensor for measuring the oil cavity pressure. The first pressure sensor, the second pressure sensor, and the inverter are respectively connected to the control unit for signal signals.

7. The piston accumulator according to claim 6, characterized in that: The control unit includes an A / D converter, an adder, and a pressure difference / torque interpolation table that are signal-connected in sequence. The A / D converter is signal-connected to the first pressure sensor and the second pressure sensor respectively, and the pressure difference / torque interpolation table is signal-connected to the inverter.

8. The piston accumulator according to any one of claims 1 to 7, characterized in that: The cylinder barrel has an air intake end cover and an oil intake end cover, and the air intake end cover and the oil intake end cover are respectively detachably connected to the cylinder barrel.

9. The piston accumulator according to claim 8, characterized in that: Sealing components are provided at the contact portions of the air intake end cover and the oil intake end cover with the cylinder barrel, at the contact portion of the air intake end cover with the piston rod, and at the contact portion of the piston with the cylinder barrel.

10. A method for controlling pressure of a piston accumulator, using the piston accumulator according to claim 7, comprising the following: S1. The first and second pressure sensors collect pressure information from the air and oil chambers, respectively. The collected pressure information is converted to digital values ​​by an A / D converter, and the difference between the two values ​​is calculated by an adder, denoted as δ1. S2. The control unit is provided with a target pressure digital value, and the difference 2 between the target pressure digital value and δ1 is calculated by the adder, recorded as δ2; S3. The difference δ2 is connected to the pressure difference / torque interpolation table, and the corresponding voltage of the torque required when the output motor is used as a motor is output. The inverter is controlled to further control the torque of the motor when used as a motor, thereby achieving a linear change in the oil pressure during the movement of the piston.

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