Pressure relief system and control method thereof

Abstract

The invention discloses a pressure relief system and a control method thereof. The technical problem that an existing pressure relief system cannot achieve slow and stable high-precision pressure relief under high pressure is solved. The pressure relief system comprises a pressure chamber used for being connected with an upstream one-way valve of a high-pressure system and a release chamber used for being connected with a downstream one-way valve of an oil return system, and the release chamber of the upstream one-way valve is communicated with the pressure chamber of the downstream one-way valve. The upstream one-way valve and the downstream one-way valve are alternately and reversely opened and closed through a crank connecting rod mechanism driven by a servo motor. The technical scheme provided by the invention not only can be applied to a cubic press or a two-sided press and can realize extremely slow pressure relief under ultrahigh pressure through continuous speed regulation operation of the oil pump, but also can be applied to various hydraulic systems with similar requirements to realize high-precision pressure control.

Description

Technical Field

[0001] The present invention relates to the technical field of high-precision pressure relief systems, and in particular to a pressure relief system and a control method thereof. Background Art

[0002] In the field of domestic superhard material synthesis, the six-sided top press or two-sided top press used in the synthesis of gem-grade diamonds and new materials research has high requirements for the pressure control accuracy and stability of the press. At present, the mainstream press of the enterprise is the Φ800 cylinder diameter six-sided top press, and its synthesis pressure is about 90MPa. In the pressure relief stage of the press, it is required to slowly release the pressure to 2MPa in 2 to 6 hours (120 to 360 minutes), the total pressure relief oil volume is about 22L, the pressure relief flow rate is about 1 to 3ml / s, and the pressure relief rate is about 0.0125MPa / s to 0.0375MPa / s, but the existing pressure relief system is difficult to meet this requirement.

[0003] For example, the invention patent application with the application publication date of 2021.12.28 and the application publication number of 2021.12.28 discloses a hydraulic system and pressure control method for a six-sided press, which are used to provide an ultra-high-pressure oil circuit, matching low-pressure and control oil circuits, and a pressure control method based on the hydraulic system for a large-cylinder six-sided press. The hydraulic oil circuit uses a reciprocating supercharger to provide ultra-high-pressure hydraulic oil, and uses a stepper motor pressure relief module for direct pressure relief.

[0004] Although the technical solution disclosed in the above invention patent application can accurately control the oil pressure of the hydraulic system, realize the long-term stable operation of the six-sided top press and the safe and stable pressure relief of the fiber insulation mortar curing device, it still cannot achieve slow, stable and high-precision pressure relief under ultra-high pressure by using a stepper motor pressure relief module for direct pressure relief. Therefore, it is necessary to design a pressure relief system that can achieve slow, stable and high-precision pressure relief under ultra-high pressure to meet the use of hydraulic systems with specific needs such as presses for synthesizing gem-grade diamonds and new materials.

[0005] It should be particularly noted that the above technical information is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as admitting or implying in any form that the above technical information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0006] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a pressure relief system and a control method thereof, which solves the technical problem that the existing pressure relief system cannot achieve slow, stable and high-precision pressure relief under high pressure.

[0007] The technical solution of this application is: A pressure relief system comprises a pressure chamber for connecting to an upstream one-way valve of a high-pressure system, and a release chamber for connecting to a downstream one-way valve of an oil return system. The release chamber of the upstream one-way valve is connected to the pressure chamber of the downstream one-way valve. The upstream one-way valve and the downstream one-way valve are opened and closed alternately in reverse by a crank-connecting rod mechanism driven by a servo motor.

[0008] On the basis of the above technical solution, as a preferred technical solution, the pressure chamber of the downstream one-way valve is connected to an oil storage tank.

[0009] On the basis of the above technical solution, as a preferred technical solution, the oil storage tank is a volume-adjustable oil storage tank.

[0010] On the basis of the above technical solution, as a preferred technical solution, the volume-adjustable oil storage tank includes an oil storage chamber volume-adjusting plunger sealed in the oil storage chamber, and the oil storage chamber volume-adjusting plunger is connected to a plunger displacement-adjusting screw.

[0011] On the basis of the above technical solution, as a preferred technical solution, the pressure chamber of the downstream one-way valve and / or the oil storage tank are connected to the oil return system through a servo throttle valve.

[0012] On the basis of the above technical solution, as a preferred technical solution, a cavity isolation check valve is provided between the pressure chamber of the downstream check valve and the servo throttle valve, or between the oil storage tank and the servo throttle valve.

[0013] On the basis of the above technical solution, as a preferred technical solution, the crank-connecting rod mechanism includes an upper eccentric cam and a lower eccentric cam arranged on a rotating camshaft, the upper eccentric cam is connected to the valve core of the upstream one-way valve through the reverse opening push rod of the upper one-way valve, and the lower eccentric cam is connected to the valve core of the downstream one-way valve through the reverse opening push rod of the lower one-way valve.

[0014] A control method for a pressure relief system, adopting the pressure relief system described in the first technical solution above; when the servo motor drives the crank-connecting rod mechanism to rotate until the upstream one-way valve is reversely opened and the downstream one-way valve is closed, the high-pressure oil of the high-pressure system enters the pressure chamber of the upstream one-way valve, the release chamber of the upstream one-way valve, and the pressure chamber of the downstream one-way valve in sequence; when the servo motor drives the crank-connecting rod mechanism to rotate until the upstream one-way valve is closed and the downstream one-way valve is reversely opened, the air stored in the oil in the pressure chamber of the downstream one-way valve expands and increases in volume, and the hydraulic oil in the pressure chamber of the downstream one-way valve is squeezed out to the oil return system through the release chamber of the downstream one-way valve; this cycle is repeated.

[0015] A control method for a pressure relief system, adopting the pressure relief system described in the second to last technical solutions of the above claims; when the servo motor drives the crank-connecting rod mechanism to rotate until the upstream one-way valve is reversely opened and the downstream one-way valve is closed, the high-pressure oil of the high-pressure system enters the pressure chamber of the upstream one-way valve, the release chamber of the upstream one-way valve, the pressure chamber of the downstream one-way valve, and the oil storage tank in sequence; when the servo motor drives the crank-connecting rod mechanism to rotate until the upstream one-way valve is closed and the downstream one-way valve is reversely opened, the air in the pressure chamber of the downstream one-way valve and the oil stored in the oil storage tank expands to increase the volume, and the pressure chamber of the downstream one-way valve and the hydraulic oil in the oil storage tank are squeezed out to the oil return system through the release chamber of the downstream one-way valve; this cycle is repeated.

[0016] On the basis of the above technical solution, as a preferred technical solution, it also includes a displacement adjustment method, adjusting the plunger displacement adjustment screw, thereby changing the volume of the oil storage chamber of the oil storage tank, thereby changing the pressure relief displacement; and / or adjusting the speed of the servo motor; When the pressure of the high-pressure system decreases, the rotation speed of the servo motor is increased and / or the volume of the oil storage chamber of the oil storage tank is increased to maintain the stability of the pressure relief flow; When the pressure of the high-pressure system is released to the low-pressure section below 10 MPa, the servo throttle valve is opened and / or the opening of the servo throttle valve is adjusted to maintain the pressure release speed unchanged.

[0017] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: Experiments show that the amount of air dissolved in mineral oil under normal conditions can reach 6% to 12%, and the amount of air dissolved in the commonly used No. 46 and No. 68 anti-wear hydraulic oils is generally about 9%, which means that under normal circumstances, the oil in the system is mixed with a certain amount of gas. According to Henry's law, the solubility of gas in oil is proportional to the absolute pressure. When the system is running, the oil will produce a large pressure drop through valves, filters and other components, causing air to precipitate and suspend in the oil in the form of tiny bubbles. The synthesis pressure in the field of superhard material synthesis is as high as 100MPa. Therefore, under the change of high and low pressures, the volume of air mixed in the hydraulic oil will change significantly, causing the volume of the hydraulic oil to change accordingly. Based on this principle and phenomenon, the present invention provides a pressure relief system and a control method thereof, wherein a downstream one-way valve and part of the pipeline are regarded as a volume chamber of G, or an oil storage tank connected to the downstream one-way valve is separately set as a volume chamber of G, and an upstream one-way valve and a downstream one-way valve are adopted. The upstream one-way valve is connected to the high-pressure chamber of the high-pressure system, and the downstream one-way valve is connected to the oil return system. By opening and closing the upstream one-way valve and the downstream one-way valve in turn, the hydraulic oil in the G chamber is alternately pressurized and relieved, and the volume of air mixed in the oil follows the compression and expansion, causing the volume of the hydraulic oil in the G chamber to change to δG. The change in volume discharges a trace amount of hydraulic oil δG back to the oil return system through the oil outlet valve, thereby realizing slow oil unloading of the high-pressure system; at the same time, through the rotation of the servo motor, the upstream one-way valve and the downstream one-way valve are driven to open and close alternately, thereby realizing stable pressure relief of the hydraulic oil.

[0018] At the same time, during the entire pressure drop process of the high-pressure system, adjusting the size of the volume chamber and / or adjusting the speed of the servo motor and / or opening and closing the servo throttle valve can maintain the stability of the pressure relief flow and keep the pressure relief speed unchanged. The technical solution provided by the present invention can not only be applied to a six-sided top press or a two-sided top press to achieve extremely slow pressure relief under ultra-high pressure through continuous speed regulation of the oil pump, but also can be applied to various hydraulic systems with similar requirements to achieve high-precision pressure control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0020] Figure 1 It is the principle diagram of the pressure relief system; Figure 2 This is the opening motion trajectory diagram of the upstream check valve and the downstream check valve.

[0021] Description of Figure Numbers: 1. Upstream one-way valve; 2. Downstream one-way valve; 3. Servo throttle valve; 4. Oil storage chamber volume adjustment plunger; 5. Plunger displacement adjustment screw; 6. Volume-adjustable oil storage tank; 7. Upstream one-way valve reverse opening push rod; 8. Downstream one-way valve reverse opening push rod; 9. Rotating camshaft; 10. Servo motor; 11. Upper eccentric cam; 12. Lower eccentric cam; 13. Cavity isolation one-way valve. DETAILED DESCRIPTION

[0022] 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 core concept of the present invention and the following embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present application provides these embodiments to make the present application thorough and complete, and to fully express the scope of the present application to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0024] It should be noted that, in the description of this application, unless otherwise specified, the meaning of "several" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", "axial", "radial" and the like indicate positions or positional relationships only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on this application. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0025] In addition, the words "first", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0026] It should also be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0027] All terms used in this application have the same meaning as those understood by those of ordinary skill in the art to which this application belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, such as general dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0028] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0029] A pressure relief system, such as Figure 1 As shown, it includes a pressure chamber for connecting to an upstream one-way valve 1 of a high-pressure system, and a release chamber for connecting to a downstream one-way valve 2 of an oil return system. The release chamber of the upstream one-way valve 1 is connected to the pressure chamber of the downstream one-way valve 2. The upstream one-way valve 1 and the downstream one-way valve 2 are alternately opened and closed in reverse by a crank-connecting rod mechanism driven by a servo motor 10.

[0030] This embodiment is the core concept of the present invention, and its most core feature is that the upstream one-way valve 1 and the downstream one-way valve 2 are opened alternately in reverse, and its key feature lies in the connection relationship between the upstream one-way valve 1 and the downstream one-way valve 2 and the high-pressure system and the low-pressure system, and its key components are the matching relationship between the upstream one-way valve 1 and the downstream one-way valve 2 and the crank-connecting rod mechanism, and secondly, the crank-connecting rod mechanism is driven by the servo motor 10.

[0031] Therefore, when the upstream one-way valve 1 is reversely opened by the crank-connecting rod mechanism, the downstream one-way valve 2 is closed, and the high-pressure oil in the high-pressure system can first enter the pressure chamber of the upstream one-way valve 1, the release chamber of the upstream one-way valve 1 and the pressure chamber of the downstream one-way valve 2 in sequence; then the crank-connecting rod mechanism reversely opens the downstream one-way valve 2, and the upstream one-way valve 1 is closed, then the oil in the release chamber of the upstream one-way valve 1, the oil in the pressure chamber of the downstream one-way valve 2, and the oil in the pipeline between the release chamber of the upstream one-way valve 1 and the pressure chamber of the downstream one-way valve 2, due to the expansion of the volume of air mixed in the oil caused by the pressure change, part of the oil in the above three spaces is squeezed into the low-pressure system; this cycle is repeated, thereby achieving stable pressure relief of the high-pressure system.

[0032] Furthermore, during the entire pressure drop process of the high-pressure system, the rotation speed of the servo motor 10 can be adjusted, which can further maintain the stability of the pressure relief flow and keep the pressure relief speed unchanged. It should be noted that the crank-connecting rod mechanism in this embodiment can have a variety of options, as long as it can ensure that the upstream check valve 1 and the downstream check valve 2 are opened alternately in reverse, and there are no special requirements for its shape, size and structure, and those skilled in the art can freely implement it according to actual needs.

[0033] On the basis of the above embodiment, as a preferred embodiment, the pressure chamber of the downstream one-way valve 2 is connected to an oil storage tank. The oil storage tank provided in this embodiment can further improve the pressure relief effect, because the air mixed in the oil in the previous embodiment is limited, and its compression and expansion effects will also be limited. This is because the amount of oil in the release chamber of the upstream one-way valve 1, the pressure chamber of the downstream one-way valve 2, and the release chamber of the upstream one-way valve 1 and the pressure chamber of the downstream one-way valve 2 are all small. A separate oil storage tank can effectively expand the amount of oil discharged to the downstream one-way valve at a time, and the air mixed in the oil will also increase accordingly. As the hydraulic oil in the oil storage tank is alternately pressurized and depressurized, the air that follows the compression and expansion can better pump the oil into the low-pressure system.

[0034] On the basis of the above embodiment, as a preferred embodiment, the oil storage tank is a volume-adjustable oil storage tank 6. In this embodiment, the oil storage tank is set to a volume-adjustable structure, which can not only further improve the oil pumping effect, but also adjust the size of the volume-adjustable oil storage tank 6 during the entire pressure drop process of the high-pressure system, which can further maintain the stability of the pressure relief flow and keep the pressure relief speed unchanged. At the same time, the volume adjustment of the volume-adjustable oil storage tank 6 can be performed alone or in conjunction with the speed adjustment of the servo motor 10.

[0035] On the basis of the above embodiment, as a preferred embodiment, the volume-adjustable oil storage tank 6 includes an oil storage chamber volume-adjusting plunger 4 sealed in the oil storage chamber, and the oil storage chamber volume-adjusting plunger 4 is connected to a plunger displacement-adjusting screw 5. This embodiment provides a preferred structural form of the volume-adjustable oil storage tank 6, and the volume of the volume-adjustable oil storage tank 6 can be changed by rotating the plunger displacement-adjusting screw 5.

[0036] As for the driving mode of the plunger displacement adjustment screw 5, there are many options, such as manual adjustment, or servo control through another servo motor. When the plunger displacement adjustment screw 5 adopts servo control, it can be incorporated into the same control system with the servo motor 10 driving the crank-connecting rod mechanism to achieve intelligent adjustment and autonomous operation. In order to improve the reliability of autonomous operation, a pressure sensor can also be set in the high-pressure system, and the pressure sensor is connected to the control system of the servo motor, so that the entire system can autonomously adjust the servo motor driving the plunger displacement adjustment screw 5 and the servo motor 10 driving the crank-connecting rod mechanism according to the pressure drop process of the high-pressure system.

[0037] On the basis of the above embodiment, as a preferred embodiment, the pressure chamber of the downstream one-way valve 2 and / or the oil storage tank is connected to the oil return system via the servo throttle valve 3. This embodiment provides three preferred implementations, namely, the pressure chamber of the downstream one-way valve 2 is connected to the oil return system via the servo throttle valve 3, or the oil storage tank is connected to the oil return system via the servo throttle valve 3, or the pressure chamber of the downstream one-way valve 2 and the oil storage tank are both connected to the oil return system via the servo throttle valve 3.

[0038] When the pressure of the high-pressure system is released to the low-pressure section below 10MPa, the pressure difference is too small, and the increase in the speed V of the servo motor 10 cannot maintain the stability of Q. At this time, the servo throttle valve 3 can be opened to bypass the pressure relief flow and maintain the pressure relief speed unchanged. If rapid pressure relief is required, the opening of the servo throttle valve 3 can also be adjusted by the servo motor SF2 to bypass the pressure relief.

[0039] On the basis of the above embodiment, as a preferred embodiment, a cavity isolation check valve 13 is provided between the pressure chamber of the downstream check valve 2 and the servo throttle valve 3, or between the oil storage tank and the servo throttle valve 3. The function of the cavity isolation check valve 13 is to isolate the inner aperture volume in the connecting pipe between the pressure chamber of the downstream check valve 2 and the servo throttle valve 3, and the inner aperture volume in the connecting pipe between the oil storage tank and the servo throttle valve 3, that is, to perform one-way isolation from the volume of the oil storage tank or the pressure chamber of the downstream check valve 2, without affecting the expansion and contraction pressure relief displacement of the cavity.

[0040] On the basis of the above embodiments, as a preferred embodiment, the crank-connecting rod mechanism includes an upper eccentric cam 11 and a lower eccentric cam 12 arranged on a rotating camshaft 9, the upper eccentric cam 11 is connected to the valve core of the upstream one-way valve 1 through an upper one-way valve reverse opening push rod 7, and the lower eccentric cam 12 is connected to the valve core of the downstream one-way valve 2 through a lower one-way valve reverse opening push rod 8.

[0041] Furthermore, in order to stabilize the displacement, a gap h is left between the upstream check valve reverse opening push rod 7 and the downstream check valve reverse opening push rod 8 and the upstream check valve 1 and the downstream check valve 2 when the eccentric cam returns to the lowest position, and h>eccentric distance e, so that the area where the upstream check valve 1 and the downstream check valve 2 are closed at the same time is ≥30°, such as Figure 2 shown.

[0042] A control method for a pressure relief system, using the pressure relief system described in the first embodiment; when the servo motor 10 drives the crank-connecting rod mechanism to rotate until the upstream one-way valve 1 is reversely opened and the downstream one-way valve 2 is closed, the high-pressure oil of the high-pressure system enters the pressure chamber of the upstream one-way valve 1, the release chamber of the upstream one-way valve 1, and the pressure chamber of the downstream one-way valve 2 in sequence; when the servo motor 10 drives the crank-connecting rod mechanism to rotate until the upstream one-way valve 1 is closed and the downstream one-way valve 2 is reversely opened, the air stored in the oil in the pressure chamber of the downstream one-way valve 2 expands and increases in volume, and the hydraulic oil in the pressure chamber of the downstream one-way valve 2 is squeezed out to the oil return system through the release chamber of the downstream one-way valve 2; this cycle is repeated.

[0043] A control method for a pressure relief system, using the pressure relief system described in the second to last embodiments of the claim; when the servo motor 10 drives the crank-connecting rod mechanism to rotate until the upstream one-way valve 1 is reversely opened and the downstream one-way valve 2 is closed, the high-pressure oil of the high-pressure system enters the pressure chamber of the upstream one-way valve 1, the release chamber of the upstream one-way valve 1, the pressure chamber of the downstream one-way valve 2, and the oil storage tank in sequence; when the servo motor 10 drives the crank-connecting rod mechanism to rotate until the upstream one-way valve 1 is closed and the downstream one-way valve 2 is reversely opened, the air in the pressure chamber of the downstream one-way valve 2 and the oil stored in the oil storage tank expands to increase its volume, and the pressure chamber of the downstream one-way valve 2 and the hydraulic oil in the oil storage tank are squeezed out to the oil return system through the release chamber of the downstream one-way valve 2; this cycle is repeated.

[0044] On the basis of the above embodiment, as a preferred embodiment, it also includes a displacement adjustment method, adjusting the plunger displacement adjustment screw 5, thereby changing the volume of the oil storage chamber of the oil storage tank, thereby changing the pressure relief displacement; and / or adjusting the speed of the servo motor 10; When the pressure of the high-pressure system decreases, the rotation speed of the servo motor 10 is increased and / or the volume of the oil storage chamber of the oil storage tank is increased to maintain the stability of the pressure relief flow; When the pressure of the high-pressure system is released to the low-pressure section below 10 MPa, the servo throttle valve 3 is opened and / or the opening of the servo throttle valve 3 is adjusted to maintain the pressure release speed unchanged.

[0045] As a preferred embodiment, an object of the present invention is to provide a top press pressure relief system, which can achieve high-precision pressure relief of the press by controlling its own rotation speed, with a pressure relief displacement of 0.1ml / r~0.3ml / r, a rotation speed adjustment range of 0~800rpm, and a pressure relief flow adjustment range of 1~4ml / s.

[0046] Hydraulic oil is incompressible under pressures below 200 MPa. However, when gas is mixed into the hydraulic oil, the volume of the gas in the hydraulic oil will be compressed under high pressure.

[0047] The relationship between air pressure and volume is: pv=nRT; In the formula, p: gas pressure; v: gas volume; n: "amount of substance" of gas; T: gas temperature; R: constant.

[0048] Experiments show that the amount of air dissolved in mineral oil under normal conditions can reach 6% to 12%. The amount of air dissolved in the commonly used No. 46 and No. 68 anti-wear hydraulic oils is generally about 9%, which means that under normal circumstances, the oil in the system is mixed with a certain amount of gas. According to Henry's law, the solubility of gas in oil is proportional to the absolute pressure. When the system is running, the oil produces a large pressure drop through valves, filters and other components, causing air to precipitate and suspend in the oil in the form of tiny bubbles. The synthesis pressure in the field of superhard material synthesis is as high as 100MPa. Therefore, under the change of high and low pressure, the volume of air mixed in the hydraulic oil will change significantly, causing the volume of the hydraulic oil to change accordingly. Based on this principle and phenomenon. Imagine designing a volume G cavity, with two valves, one connected to the high-pressure cavity of the compressor cylinder and the other connected to the oil return port of the oil tank. By opening and closing the two inlet and outlet valves in turn, the hydraulic oil in the G cavity is pressurized and depressurized alternately. The volume of air mixed in the oil is compressed and expanded, causing the volume of the hydraulic oil in the G cavity to change to δG. This volume change discharges a small amount of hydraulic oil δG back to the oil tank through the oil outlet valve, realizing the slow unloading of the high-pressure oil in the compressor cylinder.

[0049] Specific technical solutions such as Figure 1 and Figure 2 As shown, a ship lock type one-way pressure relief system is composed of a servo motor, an eccentric shaft, a bearing, a one-way valve, etc.

[0050] The motor shaft of the servomotor 10 is directly connected to the rotating camshaft 9 .

[0051] When the motor 10 rotates, the upper eccentric camshaft 11 and the lower eccentric camshaft 12 reversely open the push rod 7 through the upstream check valve and reversely open the push rod 8 through the downstream check valve, respectively reversely opening and closing the upstream check valve 1 and the downstream check valve 2. Since the two eccentric shaft sections on the rotating camshaft 9 are 180 degrees oppositely eccentric, when the upstream check valve 1 is opened, the downstream check valve 2 is closed. When the downstream check valve 2 is opened, the upstream check valve 1 is closed.

[0052] Figure 1 Position, the upper eccentric cam 11 rotates upward, and the push rod 7 is opened in the reverse direction through the upstream one-way valve, pushing the upstream one-way valve 1 to open in the reverse direction, and the lower eccentric cam 12 rotates downward, the push rod 8 of the downstream one-way valve is opened in the reverse direction and retreats, and the downstream one-way valve 2 is closed.

[0053] The high-pressure oil Q enters the pressure chamber of the upstream one-way valve 1 through the P port. Since the valve core of the upstream one-way valve 1 is open, the high-pressure oil Q enters the release chamber of the upstream one-way valve 1. Since the release chamber of the upstream one-way valve 1 and the adjustable volume oil storage tank 6 are connected to the pressure chamber of the downstream one-way valve 2 by a channel, the high-pressure oil enters the adjustable volume oil storage tank 6. The high-pressure oil with a volume of G and a pressure of P is stored.

[0054] When the rotating camshaft 9 rotates 180°, the upstream one-way valve 1 is closed and the downstream one-way valve 2 is opened. Since the release chamber of the downstream one-way valve 2 is connected to the outlet T1 and the oil tank through the channel, after the downstream one-way valve 2 is opened, the pressure in the G chamber drops to 0, and the air in the oil stored in the G chamber expands and increases in volume to δG, squeezing the oil in the G chamber out of the T1 port and back to the oil tank.

[0055] Every time the eccentric shaft rotates one circle, the upstream check valve 1 and the downstream check valve 2 are opened once respectively, discharging δG amount of hydraulic oil. The volume adjustment plunger 4 of the oil storage chamber can be moved by the plunger displacement adjustment screw to adjust the volume G of the adjustable volume oil storage tank, thereby changing the pressure relief displacement δG.

[0056] At the same time, the speed V of the servo motor 10 can also be adjusted to change the size of the pressure relief flow Q by the pressure relief flow Q = V × δG. As the pressure P decreases, the pressure difference decreases, and the displacement δG decreases accordingly. The pressure relief flow Q can be maintained stable by increasing the speed of the motor 10.

[0057] In addition, when the pressure is released to the low-pressure section below 10MPa, the pressure difference is too small, and the increase in the speed V cannot maintain the stability of Q. At this time, the servo throttle valve 3 can be opened to bypass the pressure relief flow and maintain the pressure relief speed unchanged. If rapid pressure relief is required, the servo throttle valve 3 opening can also be adjusted by the servo motor SF2 to bypass the pressure relief.

[0058] The function of the upstream one-way valve 13 is to isolate the inner aperture volume in the connecting pipe between the oil storage chamber 6 and the servo throttle valve 3 from the volume G of the oil storage chamber 6 in one direction without affecting the expansion and contraction pressure relief displacement δG of the G chamber.

[0059] The pressure relief system provided by the present invention can be used alone as a pressure relief device for a two-sided top press or a six-sided top press, and can also be used in conjunction with other pressure relief devices to achieve high-precision pressure control.

[0060] A more specific implementation is as follows: Among them, the rated pressure of the oil pump is 100MPa, the pressure relief displacement is 0.1ml / r~0.3ml / r, the speed adjustment range is 0~800rpm, and the pressure relief flow adjustment range is 1~4ml / s.

[0061] According to the gas state equation theorem in physics, when the ambient temperature is constant, the pressure of the gas is inversely proportional to its volume change, that is, p1×v1=p2×v2, for example: when p1=10 MPa; p2=0.1 MPa; then v1=0.01v2.

[0062] According to the fact that the amount of air dissolved in hydraulic oil is generally about 9%, the designed pressure relief displacement δG is 0.1ml / r ~ 0.3ml / r, and the volume of G is 1.1 cubic centimeters ~ 3.3 cubic centimeters. The design takes the adjustable range of G = 0.5 cubic centimeters ~ 5 cubic centimeters.

[0063] The motor drives the rotating camshaft to complete a pressure relief and oil discharge every time it rotates 360°. The rotating camshaft 9 rotates in the following working phase sequence: 1. Starting point 0°~15°: both the upstream check valve 1 and the downstream check valve 2 are closed. The oil storage volume in the adjustable oil storage tank 6 is G, and the pressure is 0.

[0064] 2. 15°~165° range: upstream check valve 1 is open; downstream check valve 2 is closed. High-pressure oil P enters the volume-adjustable oil storage tank 6 through the upstream check valve 1, with a storage volume of G and a pressure of P.

[0065] 3. 165°~195° range: upstream check valve 1 is closed; downstream check valve 2 is closed. High-pressure oil is enclosed in the adjustable oil storage tank 6, the oil storage volume is G, and the pressure is P.

[0066] 4. 195°~345° range: upstream check valve 1 is closed; downstream check valve 2 is opened. The adjustable volume oil storage tank 6 is connected to the oil outlet T1 through the downstream check valve 2, the hydraulic oil expands and discharges the δG capacity oil back to the oil tank through the T1 port, and the pressure of the adjustable volume oil storage tank 6 drops to 0.

[0067] 5. 345°~360° range: upstream check valve 1 is closed; downstream check valve 2 is closed. The oil storage volume in the adjustable oil storage tank 6 is G, and the pressure is 0.

[0068] The key points and protection points of the present invention include the following: 1. The structure and principle of a pressure relief system. The two eccentric shaft sections on the rotating camshaft 9 are 180 degrees oppositely eccentric. Therefore, when the upstream check valve 1 is opened, the downstream check valve 2 is closed. When the downstream check valve 2 is opened, the upstream check valve 1 is closed.

[0069] 2. The release chamber of the upstream one-way valve 1 and the volume-adjustable oil storage tank 6 are both connected to the pressure chamber of the downstream one-way valve 2 via a channel. The release chamber of the downstream one-way valve 2 is connected to the outlet T1 via a channel and is connected to the oil tank.

[0070] 3. The volume of the chamber can be adjusted: the oil storage chamber volume adjustment plunger 4 can be moved by the plunger displacement adjustment screw, and the volume G of the adjustable volume oil storage tank can be adjusted, thereby changing the pressure relief displacement δG.

[0071] 4. G cavity is connected in parallel with servo throttle valve 3. However, when the pressure is released to the low-pressure section, the pressure difference is too small, and the increase in speed V cannot maintain the stability of Q. At this time, the servo throttle valve 3 can be opened to bypass the pressure relief flow and maintain the pressure relief speed unchanged. It can also be used to bypass and open fast pressure relief.

[0072] 5. The setting of the isolation upstream one-way valve 13 isolates the inner aperture volume in the connecting pipe between the volume-adjustable oil storage tank 6 and the servo throttle valve 3 from the volume G of the volume-adjustable oil storage tank 6 in one direction without affecting the expansion and contraction pressure relief displacement δG of the G volume chamber.

[0073] 6. In order to stabilize the displacement δG, a gap h is left between the upstream check valve reverse opening push rod 7 and the downstream check valve reverse opening push rod 8 and the upstream check valve 1 and the downstream check valve 2 when the eccentric cam returns to the lowest position, and h> eccentric distance e. The area where the upstream check valve 1 and the downstream check valve 2 are closed at the same time is ≥30°. Figure 2 shown.

[0074] The details not described in detail in the present invention are all conventional technical means known to those skilled in the art.

[0075] The above content shows and describes the basic principles, main features and beneficial effects of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pressure relief system, characterized in that: The invention comprises a pressure chamber for connecting to an upstream one-way valve (1) of a high-pressure system, and a release chamber for connecting to a downstream one-way valve (2) of an oil return system, wherein the release chamber of the upstream one-way valve (1) is connected to the pressure chamber of the downstream one-way valve (2), and the upstream one-way valve (1) and the downstream one-way valve (2) are opened and closed alternately in reverse directions via a crank connecting rod mechanism driven by a servo motor (10).

2. The pressure relief system according to claim 1, characterized in that: The pressure chamber of the downstream one-way valve (2) is connected to an oil storage tank.

3. The pressure relief system according to claim 2, characterized in that: The oil storage tank is a volume-adjustable oil storage tank (6).

4. The pressure relief system according to claim 3, characterized in that: The volume-adjustable oil storage bin (6) comprises an oil storage chamber volume-adjusting plunger (4) which is sealed in the oil storage chamber, and the oil storage chamber volume-adjusting plunger (4) is connected to a plunger displacement-adjusting screw (5).

5. The pressure relief system according to any one of claims 2 to 4, characterized in that: The pressure chamber of the downstream one-way valve (2) and / or the oil storage tank are connected to the oil return system via a servo throttle valve (3).

6. The pressure relief system according to claim 5, characterized in that: A cavity isolation check valve (13) is provided between the pressure chamber of the downstream check valve (2) and the servo throttle valve (3), or between the oil storage tank and the servo throttle valve (3).

7. The pressure relief system according to any one of claims 1 to 4 and 6, characterized in that: The crank-connecting rod mechanism comprises an upper eccentric cam (11) and a lower eccentric cam (12) arranged on a rotating camshaft (9); the upper eccentric cam (11) is connected to the valve core of the upstream one-way valve (1) via an upper one-way valve reverse opening push rod (7); and the lower eccentric cam (12) is connected to the valve core of the downstream one-way valve (2) via a lower one-way valve reverse opening push rod (8).

8. A method for controlling a pressure relief system, characterized in that: Using the pressure relief system described in claim 1; When the servo motor (10) drives the crank-connecting rod mechanism to rotate until the upstream one-way valve (1) is reversely opened and the downstream one-way valve (2) is closed, the high-pressure oil of the high-pressure system sequentially enters the pressure chamber of the upstream one-way valve (1), the release chamber of the upstream one-way valve (1), and the pressure chamber of the downstream one-way valve (2); When the servo motor (10) drives the crank-connecting rod mechanism to rotate until the upstream one-way valve (1) is closed and the downstream one-way valve (2) is reversely opened, the air in the oil stored in the pressure chamber of the downstream one-way valve (2) expands and increases in volume, and the hydraulic oil in the pressure chamber of the downstream one-way valve (2) is squeezed out to the oil return system through the release chamber of the downstream one-way valve (2); this cycle repeats.

9. A method for controlling a pressure relief system, characterized in that: A pressure relief system according to any one of claims 2 to 7; When the servo motor (10) drives the crank-connecting rod mechanism to rotate until the upstream one-way valve (1) is reversely opened and the downstream one-way valve (2) is closed, the high-pressure oil of the high-pressure system sequentially enters the pressure chamber of the upstream one-way valve (1), the release chamber of the upstream one-way valve (1), the pressure chamber of the downstream one-way valve (2), and the oil storage tank; When the servo motor (10) drives the crank-connecting rod mechanism to rotate until the upstream one-way valve (1) is closed and the downstream one-way valve (2) is reversely opened, the air in the pressure chamber of the downstream one-way valve (2) and the oil stored in the oil storage tank expands and increases in volume, and the hydraulic oil in the pressure chamber of the downstream one-way valve (2) and the oil storage tank is squeezed out to the oil return system through the release chamber of the downstream one-way valve (2); this cycle repeats.

10. The control method of the pressure relief system according to claim 9, characterized in that: Also included is a displacement adjustment method, which adjusts the plunger displacement adjustment screw (5) to change the volume of the oil storage chamber of the oil storage tank, thereby changing the pressure relief displacement; and / or adjusting the rotation speed of the servo motor (10); When the pressure of the high-pressure system decreases, the rotation speed of the servo motor (10) is increased and / or the volume of the oil storage chamber of the oil storage tank is increased to maintain the stability of the pressure relief flow; When the pressure of the high-pressure system is released to a low-pressure section below 10 MPa, the servo throttle valve (3) is opened and / or the opening of the servo throttle valve (3) is adjusted to maintain a constant pressure release speed.

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