Piston type energy accumulator and pressure control method

Abstract

The invention discloses a piston type energy accumulator and a pressure control method, and belongs to the technical field of energy accumulators, the piston type energy accumulator comprises a cylinder barrel capable of forming a closed cavity, a piston assembly and a driving assembly used for driving the piston assembly to move, and the piston assembly comprises a piston and a piston rod fixedly connected with the piston; the piston is arranged in the cylinder barrel and divides a cavity in the cylinder barrel into an air cavity and an oil cavity, the air cavity is communicated with an air source, the oil cavity is communicated with an oil source, the piston rod penetrates through and extends out of the air cavity, and the end, extending out of the air cavity, of the piston rod is in transmission connection with the driving assembly. The piston can be driven to move left and right under the action of the driving assembly and the pressure difference between the air cavity and the oil cavity; the driving part makes up the difference between the oil pressure and linear change when the piston is only under the action of differential pressure, and the problem of nonlinear change of the oil pressure of the energy accumulator is solved.

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] The piston accumulator plays the role of pressure stabilization and energy recovery and reuse in the hydraulic system. Its working principle is: the piston separates the cylinder into an air chamber and an oil chamber, and the oil chamber is connected to the hydraulic pipeline. When the pressure of the hydraulic system fluctuates due to the load during operation, the high-pressure gas of the accumulator acts on the oil chamber through the piston, which can effectively reduce the pressure fluctuation; when the accumulator is used for energy recovery and reuse of the hydraulic system, this type of hydraulic system is often a liquid-gas balance system, and the system is applied to mobile engineering machinery. The accumulator pressure is used to balance the gravity of the working device. When the working device descends, the accumulator recovers energy, and when the working device rises, the accumulator releases the stored energy. The problem that the accumulator often encounters during the use of this system is the nonlinear change of the accumulator oil pressure. At present, the solution to this problem is mostly to reduce the impact of the nonlinear change of the accumulator oil pressure on the system operation control through valve control, and the essential problem of its nonlinear change has not been solved.

[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 provide a piston accumulator and a pressure control method to solve the problem of nonlinear change of oil pressure of the accumulator in view of the defects and shortcomings in the prior art.

[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 driving 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 is arranged 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, 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 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.

[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 electrical machine can be used both as a motor and as 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, and the first pressure sensor, the second pressure sensor and the inverter are respectively connected to the control unit by signal.

[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, sealing components are provided at the contact portions between the air intake end cover and the oil intake end cover and the cylinder barrel, at the contact portion between the air intake end cover and the piston rod, and at the contact portion between the piston and the cylinder barrel.

[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 pressure sensor and the second pressure sensor respectively collect pressure information of the air cavity and the oil cavity, and the collected pressure information is converted into a digital quantity by an A / D converter, and the difference between the two is calculated by an adder, which is 1 and recorded as δ1;

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

[0018] S3. The difference δ2 is connected to the pressure difference / torque interpolation table, the corresponding voltage of the torque required when the output motor is used as a motor is output, and the inverter is controlled to further control the torque of the motor when it is used as a motor, so as to realize the linear change of 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 the problem of nonlinear change of accumulator oil pressure by connecting the piston rod to the driving assembly and moving it left and right under the action of the driving assembly and the pressure difference between the air chamber and the oil chamber. Compared with the prior art method of realizing the left and right movement of the piston only by the pressure difference between the air chamber and the oil chamber, the present invention sets a fixed connection between the piston rod and the piston, and moves under the joint action of the driving assembly and the pressure difference.

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

[0022] 2. The present invention can more accurately control the torque of the motor by setting 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

[0024] Figure 1 It 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 The figure is a schematic diagram of the operation 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. Inlet cover; 11. Piston rod; 12. Power supply; 13. Control unit. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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, including a cylinder 5 that can form a closed cavity, a piston assembly, and a driving 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 placed inside the cylinder 5 and divides the cavity inside the cylinder 5 into an air cavity 9 and an oil cavity 7. The air cavity 9 is connected to an air source, and the oil cavity 7 is connected to an oil source. The piston rod 11 penetrates and extends out of the air cavity 9, and one end extending out of the air cavity 9 is transmission-connected to the driving assembly, and can drive the piston 8 to move left and right under the action of the driving assembly and the pressure difference between the air cavity 9 and the oil cavity 7. The movement process of the piston 8 is described by taking the air cavity 9 on the left and the oil cavity 7 on the right as an example. When the pressure in the air chamber 9 is less 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 greater 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 driving component makes up for the gap between the oil pressure and the linear change when the piston 8 is only under the action of the pressure difference, thereby solving the problem of nonlinear change of the oil pressure in the accumulator.

[0030] The driving assembly can be a gear rack structure, an electric push rod structure, etc., and 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 pressure difference is made up. In one embodiment, the driving 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 adapted to 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 pressure difference is made up. The motor 2 used in this embodiment can be used as both an electric motor and a generator, such as the motor used in existing new energy vehicles. When the pressure of the oil chamber 7 is greater than the pressure of the air chamber 9 and the piston 8 moves to the left, the motor 2 is used as a generator. At this time, the piston rod 11 pushes the ball screw 3 to rotate and drives the generator to generate electricity, and the electricity is stored in the power supply 12. The internal thread of the piston rod 11 will not have a thread self-locking phenomenon during the movement, so as to ensure that the rotation of the ball screw 3 can drive the piston rod 11 to move, and the movement of the piston rod 11 can also push the ball screw 3 to rotate; when the pressure of the oil chamber 7 is less than the pressure of the air chamber 9, and the piston 8 needs to move to the right, the motor 2 is used as an electric motor to drive the ball screw 3 to rotate and assist and adjust the piston 8 to move to the right, so as 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 of the air chamber 9, and a second pressure sensor for measuring the pressure of the oil chamber 7. The first pressure sensor, the second pressure sensor, and the inverter 1 are respectively connected to the control unit 13 by signals. The control unit 13 adjusts the operating parameters of the motor 2 according to the pressure data measured by the first pressure sensor and the second pressure sensor.

[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 in signal connection. The A / D converter is respectively connected in signal connection with the first pressure sensor and the second pressure sensor, and the pressure difference / torque interpolation table is connected in signal connection with the inverter 1. The adder used here is a device which can calculate the difference after being set.

[0033] refer to Figure 1 The cylinder barrel 5 has an air intake cover 10 and an oil intake cover 6, which are detachably connected to the cylinder barrel 5 to facilitate replacement of damaged parts. The contact parts of the air intake cover 10 and the cylinder barrel 5, the contact parts of the oil intake cover 6 and the cylinder barrel 5, the contact parts of the air intake cover 10 and the piston rod 11, and the contact parts of the piston 8 and the cylinder barrel 5 are all provided with sealing parts 4 to prevent leakage.

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

[0035] S1. The first pressure sensor and the second pressure sensor respectively collect pressure information of the air cavity 9 and the oil cavity 7, the collected pressure information is converted into a digital quantity by an A / D converter, and the difference between the two is calculated by an adder, which is 1 and recorded as δ1;

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

[0037] S3. The difference δ2 is connected to the pressure difference / torque interpolation table, the corresponding voltage of the torque required when the output motor 2 is used as a motor is output, and the inverter 1 is controlled to further control the torque of the motor 2 when it is used as a motor, so as to realize the linear change of 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 above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A piston accumulator, characterized in that: It includes 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 includes 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, 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.

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 supplying power to 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 drivingly connected to the motor.

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

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 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.

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 between the air intake end cover and the oil intake end cover and the cylinder barrel, at the contact portions between the air intake end cover and the piston rod, and at the contact portions between the piston and the cylinder barrel.

10. A method for controlling the pressure of a piston accumulator, using the piston accumulator according to claim 7, comprising the following contents: S1. The first pressure sensor and the second pressure sensor respectively collect pressure information of the air cavity and the oil cavity, and the collected pressure information is converted into a digital quantity by an A / D converter, and the difference between the two is calculated by an adder, which is 1 and recorded as δ1; S2. The control unit is provided with a target pressure digital quantity, and the difference 2 between the target pressure digital quantity and δ1 is calculated by an adder, which is recorded as δ2; S3. The difference δ2 is connected to the pressure difference / torque interpolation table, the corresponding voltage of the torque required when the output motor is used as a motor is output, and the inverter is controlled to further control the torque of the motor when it is used as a motor, so as to realize the linear change of the oil pressure during the movement of the piston.

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