Oil return buffer device and impact test system having the same

Abstract

The application discloses an oil return buffer device and an impact test system with the same, and belongs to the technical field of impact test systems. The oil return buffer device comprises a cylinder assembly, a buffer piston, an impact piston, an overflow detection circuit, an oil filling detection circuit and an air filling detection circuit. The cylinder assembly is internally provided with a first inner cylinder cavity, a damping hole and a buffer cavity, and the buffer cavity is connected with the oil filling detection circuit. The buffer piston is arranged in the first inner cylinder cavity so as to divide the first inner cylinder cavity into a first side cavity and a second side cavity. The buffer piston is provided with a second inner cylinder cavity, and the impact piston is arranged in the second inner cylinder cavity so as to divide the second inner cylinder cavity into an oil return cavity and an air cavity. The oil return cavity is communicated with the first side cavity, and the air cavity is communicated with the air filling detection circuit. In the device, there are obvious impact and buffer stages. In the impact stage, the impact pressure is rapidly reduced, and in the buffer stage, the deceleration back pressure is obtained by means of oil pressure pressure loss. The buffer effect is obvious and easy to control, and the device is suitable for the high-speed and large-flow oil return buffer field of an impact hydraulic system.

Description

Technical Field

[0001] The present invention relates to the technical field of high-speed hydraulic equipment, and in particular to an oil return buffer device. In addition, the present invention also relates to an impact test system including the oil return buffer device. Background Art

[0002] In various engineering applications, such as high-speed impact testing or high-speed ejection devices, test blocks or objects of varying masses often need to be accelerated to a target speed within a specified stroke. Hydraulic systems, with their advantages of high load capacity and compact structure, are ideal acceleration systems. During acceleration, hydraulic systems often accelerate the return oil, resulting in high speed and high flow rates. To prevent damage to the hydraulic system caused by high-speed, high-flow return oil, the return oil must be buffered and decelerated. As a buffering actuator, the buffer device should feature low return oil resistance during acceleration, high load capacity during buffering, and high speed.

[0003] Patent 1: CN220378618U discloses a buffer oil storage device and impact test system, comprising a cylinder and a piston, wherein the piston is used to separate the inner cavity of the cylinder into an air cavity located at the first end of the cylinder and an oil cavity located at the second end of the cylinder; an exhaust hole is provided on the end surface of the first end of the cylinder and connected to the inner wall of the first end of the cylinder; the second end of the cylinder is used to connect and communicate with the oil source of the acceleration system; an air supply device is provided outside the cylinder body, which is used to fill the air cavity of the cylinder with inert gas so that when the acceleration system is activated, the oil source fills the oil cavity with hydraulic oil to form a buffer deceleration for the piston when it moves toward the first end of the cylinder; the cylinder body is also provided with an adjustment component for adjusting the stroke of the piston and thus adjusting the oil storage capacity of the cylinder. In this patented device, buffer deceleration is mainly achieved by inert gas, and there is no obvious impact stage and buffer stage. The return oil resistance is large in the impact stage, and the deceleration back pressure is obtained only by gas pressure loss in the buffer stage, making the buffering effect difficult to control.

[0004] Patent application 2: CN117432452A discloses an anti-impact hydraulic support device, a hydraulic support, and a control method. The support device includes: a first sleeve; a piston rod, which is mounted in the first sleeve, and has a first piston mounted in the first sleeve. The first piston divides the first sleeve into a first chamber and a second chamber, and the first chamber is connected to a first pipeline. The support device also includes: a first solenoid valve, which is mounted in the first chamber of the first sleeve; a sensor, which can monitor the impact of the top of the piston rod; and a control unit connected to the sensor and the first solenoid valve. The control unit controls the first solenoid valve to open when the value monitored by the sensor is greater than a set threshold, so that the medium on the lower side of the first piston can enter the upper side of the first piston. This patented device is mainly used to prevent external physical impact, such as roof support in coal mining, and transient impact generated by support structures during some building construction and civil engineering construction. It is not suitable for the high-speed and high-flow return oil buffering field of impact hydraulic systems.

[0005] Patent application 3: CN105715612A discloses a throttling buffer oil cylinder with an integrated buffer cylinder bottom. The cylinder includes a cylinder barrel, a cylinder bottom, a piston, and a piston rod. The cylinder bottom is provided with a buffer plunger on the side facing the piston, and the piston is provided with a buffer cavity on the side facing the cylinder bottom. When the piston approaches the end of its stroke, the buffer plunger extends into the buffer cavity. The buffer plunger is a hollow structure, and the cylinder bottom is provided with an oil hole connected to the inner cavity of the buffer plunger. In this patent, it is suitable for low-speed buffering of conventional oil cylinders and cannot meet the buffering requirements of high-speed, high-flow oil return.

[0006] In the existing technology, there are three main types of oil return buffering technologies for high speed and large flow. The first is to use the medium flow resistance between the piston gap and the inner surface of the cylinder body for buffering braking. The instantaneous buffering pressure of the buffer chamber of this method cannot be reduced. As time goes by and the number of buffering times increases, the higher buffering pressure will cause damage to the piston and cylinder, such as patent CN220378618U; the second is a throttling buffering method using an integrated buffer cylinder bottom to integrate the buffering position on the piston. This method is only suitable for low-speed oil cylinders and cannot meet the buffering requirements of high-speed and large-flow return oil, such as patent application CN105715612A; the third is to connect a buffer device to the acceleration device to perform buffering by throttling and accumulators. The existing buffer device using this technology has high resistance in the acceleration stage and cannot meet the demand for instantaneous large flow during high-speed impact. Summary of the Invention

[0007] The present invention provides an oil return buffer device and an impact test system having the same, so as to solve the technical problems existing in existing devices and systems, such as no obvious impact stage and buffer stage, large oil return resistance in the impact stage, only relying on gas pressure loss to obtain deceleration back pressure in the buffer stage, difficult to control the buffering effect, and inability to meet the buffering requirements of high-speed and large-flow oil return.

[0008] The technical solution adopted in the present invention is as follows:

[0009] An oil return buffer device comprises: a cylinder assembly, a buffer piston, an impact piston, an overflow detection circuit, an oil filling detection circuit and an air filling detection circuit; the cylinder assembly is hollow cylindrical for connecting to an impact test system, and has a first inner cylinder cavity arranged along the axial direction, and a buffer cavity connected to the first inner cylinder cavity through a damping hole, the buffer cavity is connected to the oil filling detection circuit, so as to perform oil filling and pressure detection on the buffer cavity through the oil filling detection circuit; the buffer piston is slidably arranged in the first inner cylinder cavity to separate the first inner cylinder cavity into a first side cavity and a second side cavity located on both sides thereof and not connected cavity, and the second side cavity is connected to the buffer cavity through the damping hole; the buffer piston is hollow cylindrical and has a second inner cylinder cavity arranged along the axial direction, and the impact piston is slidably arranged in the second inner cylinder cavity to separate the second inner cylinder cavity into a return oil cavity and an air cavity located on both sides thereof and not connected, and the return oil cavity is connected to the first side cavity for connection with the impact return oil of the impact test system, and the return oil cavity is also connected to the overflow detection circuit for the lubricating oil in the return oil cavity to overflow outward and for pressure detection, and the air cavity is connected to the inflation detection circuit to inflate the air cavity, perform pressure detection and discharge the gas in the air cavity to the atmosphere.

[0010] Furthermore, the oil return buffer device also includes a buffer piston rod axially connected to the buffer piston, and the buffer piston rod is located in the second side cavity so that the second side cavity forms a rod cavity; the cylinder assembly includes a hollow cylindrical cylinder, a first end cover for closing the second end of the cylinder, and a first end cover cylinder body axially connected to the first end cover for accommodating the buffer piston rod, and the first end of the cylinder is connected to the oil return cavity; the buffer piston is slidably arranged in the inner cylinder cavity of the cylinder, and the two are also sealed by a sealing ring; the buffer piston rod axially penetrates the rod cavity and extends into the first end cover cylinder body, and the buffer piston rod and the first end cover cylinder body are also sealed by a sealing ring.

[0011] Furthermore, the first end cover cylinder is in the shape of a hollow cylinder with both ends connected; the cylinder assembly also includes a third end cover for closing the free end of the first end cover cylinder, and the third end cover is provided with an air hole set through it, and the air hole is connected to the inflation detection circuit; the buffer piston rod is in the shape of a hollow cylinder with both ends connected, and the two ends of the buffer piston rod are respectively connected to the air cavity and the inner cylinder cavity of the first end cover cylinder, so that the air cavity is connected to the inner cylinder cavity of the buffer piston rod and the inner cylinder cavity of the first end cover cylinder in turn.

[0012] Furthermore, the inflation detection circuit includes an air supply pipeline connected to the air hole, and a second needle valve, an air cavity pressure sensor and an electric ball valve connected to the air supply pipeline.

[0013] Furthermore, the cylinder assembly also includes a second end cover that is sleeved on the outer circle of the first end cover barrel and located outside the first end cover. The second end cover is concave to form a buffer cavity between it and the first end cover. The second end cover is also provided with a buffer oil port that is through-set and connected to the buffer cavity, and the buffer oil port is connected to the oil filling detection circuit; the damping hole is a multi-circle annular hole opened on the first end cover and in the shape of a concentric ring, so that the rod cavity and the buffer cavity are connected through the multi-circle annular hole.

[0014] Furthermore, the cylinder assembly also includes a second end cover that is annular and sealingly sleeved on the outer circle of the cylinder. The second end cover is concave to form a buffer cavity between it and the cylinder. The second end cover is also provided with a buffer oil port that is arranged through and connected to the buffer cavity. The buffer oil port is connected to the oil filling detection circuit; the damping hole is a multi-circle damping hole group that is opened in sequence on the cylinder along the axial direction, and each circle of the damping hole group includes a plurality of damping holes that are arranged in sequence along the circumferential direction to connect the rod cavity and the buffer cavity through the damping hole group.

[0015] Furthermore, the diameters of the damping holes of the multi-ring damping hole group gradually decrease along the damping sliding direction of the buffer piston.

[0016] Furthermore, the oil filling detection circuit includes an oil delivery pipeline connected to the buffer oil port, and a ball valve and a buffer chamber pressure sensor connected to the oil delivery pipeline.

[0017] Furthermore, the oil filling detection circuit also includes a piston accumulator connected to the oil pipeline, and the piston accumulator is provided with a separate air filling chamber and oil filling chamber. The air filling chamber is also connected to an external inert gas source through a first needle valve, and the oil filling chamber is connected to the buffer oil port.

[0018] Furthermore, the cylinder assembly also includes a piston cover located in the first side cavity, which is used to axially abut the corresponding end of the buffer piston, and the piston cover partially extends into the return oil cavity to abut against the impact piston to prevent the impact piston from sliding out of the buffer piston.

[0019] Furthermore, the overflow detection circuit includes an overflow pipeline connected to the oil return chamber, and an oil return chamber pressure sensor, an electromagnetic ball valve and an overflow valve connected in sequence to the overflow pipeline.

[0020] According to another aspect of the present invention, an impact test system is further provided, wherein the oil return pipe or the high-speed switching valve group is connected to any of the above-mentioned oil return buffer devices.

[0021] The present invention has the following beneficial effects:

[0022] In the oil return buffer device of the present invention, a dual piston of an impact piston and a buffer piston is used to realize acceleration and buffering action. An impact piston is designed inside the buffer piston. In the impact stage, one end of the impact piston is a high-speed and large-flow oil return, and the other end is an air cavity connected to the atmosphere, so that the impact hydraulic system has almost no oil return back pressure in the acceleration stage. When the impact piston moves to the end of the stroke, it enters the buffer stage, and the buffer piston plays a deceleration and buffering role to realize the buffering and deceleration of the oil. Therefore, in the oil return buffer device of the present invention, through the cooperation of the impact piston and the buffer piston, the entire impact buffering process has obvious impact stage and buffering stage. The oil return resistance in the impact stage is small (the air cavity is connected to the atmosphere), and the instantaneous impact pressure in the impact stage is rapidly reduced, which is not easy to cause damage to the cylinder assembly and the piston. In the buffer stage, the deceleration back pressure is obtained by relying on the oil pressure loss. The buffering effect is obvious and easy to control, and it is suitable for the high-speed and large-flow oil return buffer field of the impact hydraulic system.

[0023] In the impact test system of the present invention, the entire impact buffering process has obvious impact stage and buffering stage. The return oil resistance in the impact stage is small, and the instantaneous impact pressure in the impact stage decreases rapidly, which is not easy to cause damage to the cylinder assembly and the piston. In the buffering stage, the deceleration back pressure is obtained by relying on the oil pressure loss. The buffering effect is obvious and easy to control, and it is suitable for the high-speed and large-flow return oil buffering field of the impact hydraulic system.

[0024] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is a schematic structural diagram of the oil return buffer device before the impact begins in a preferred embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the oil return buffer device at the start of buffering in the preferred embodiment of the present invention. Figure 1 ;

[0028] Figure 3 2. It is a structural schematic diagram showing the impact piston and the buffer piston in the oil return buffer device of the preferred embodiment of the present invention extended to the limit position;

[0029] Figure 4 This is a schematic diagram of the structure of the oil return buffer device at the start of buffering in the preferred embodiment of the present invention. Figure 2 .

[0030] Legend:

[0031] 100, impact oil return; 110, oil return chamber; 120, oil return chamber pressure sensor; 130, electromagnetic ball valve; 140, relief valve; 210, cylinder barrel; 211, first end face of cylinder body; 212, second end face of cylinder body; 213, first stopper; 220, piston cover; 221, second stopper; 230, impact piston; 240, buffer piston; 241, buffer piston rod; 242, rod chamber; 250, first end cover; 251, damping Hole; 252, first end cover cylinder; 260, second end cover; 261, buffer oil port; 262, buffer cavity; 270, third end cover; 271, air hole; 272, air cavity; 300, oil filling detection circuit; 310, first needle valve; 320, piston accumulator; 330, ball valve; 340, buffer cavity pressure sensor; 400, inflation detection circuit; 410, second needle valve; 420, air cavity pressure sensor; 430, electric ball valve. DETAILED DESCRIPTION

[0032] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0033] Reference Figure 1 and Figure 4 A preferred embodiment of the present invention provides an oil return buffer device, comprising: a cylinder assembly, a buffer piston 240, an impact piston 230, an overflow detection circuit, an oil filling detection circuit 300, and an air filling detection circuit 400. The cylinder assembly is hollow and cylindrical for connection to an impact test system, and comprises a first inner cylinder cavity arranged axially therein, and a buffer cavity 262 connected to the first inner cylinder cavity via a damping hole 251. The buffer cavity 262 is connected to the oil filling detection circuit 300, so that the buffer cavity 262 can be filled with oil and pressure detected by the oil filling detection circuit 300. The buffer piston 240 is slidably disposed in the first inner cylinder cavity to separate the first inner cylinder cavity into a first side cavity and a second side cavity located on either side of the first inner cylinder cavity and not connected thereto. The second side cavity is connected to the buffer cavity 262 via the damping hole 251. The buffer piston 240 is hollow cylindrical and has a second inner cylinder cavity arranged along the axial direction. The impact piston 230 is slidably set in the second inner cylinder cavity to separate the second inner cylinder cavity into a return oil cavity 110 and an air cavity 272 located on both sides thereof and not connected. The return oil cavity 110 is connected to the first side cavity and is used to connect with the impact return oil 100 of the impact test system. The return oil cavity 110 is also connected to the overflow detection circuit for the lubricating oil in the return oil cavity 110 to overflow and pressure detection. The air cavity 272 is connected to the inflation detection circuit 400 to inflate the air cavity 272, detect the pressure and discharge the gas in the air cavity 272 to the atmosphere through the inflation detection circuit 400.

[0034] The oil return buffer device of the present invention is divided into a preparation stage, an impact stage, and a buffer stage. The specific working process is as follows:

[0035] Preparation stage: The oil return buffer device of the present invention is arranged at the oil return position of the high-speed switch valve of the impact system. The impact return oil 100 is connected to the oil return of the high-speed switch valve. At this time, the high-speed switch valve is not opened, the overflow detection circuit is opened and the pressure is set to 10-20 bar;

[0036] Open the oil filling detection circuit 300, and fill the buffer chamber 262 and the second side chamber with oil from the external high-pressure oil source, so that the buffer piston 240 retracts to the rightmost position, as shown in FIG. Figure 1 As shown, when the overflow detection circuit detects that the pressure of the oil return chamber 110 is maintained at the first set value, it is considered that the buffer piston 240 is retracted into position, and then the oil filling detection circuit 300 is closed after the pressure of the buffer chamber 262 is detected to be maintained at the target pressure.

[0037] Open the inflation detection circuit 400, connect the external high-pressure nitrogen to inflate the air chamber 272, and the inflation pressure is 10-15 bar higher than the impact return oil pressure, so that the impact piston 230 retracts to the rightmost position, such as Figure 1 As shown, when the overflow detection circuit detects that the pressure of the oil return chamber 110 is maintained at the second set value, it is considered that the impact piston 230 is retracted into position, and then the pressure of the air chamber 272 is maintained at the target pressure and the inflation detection circuit 400 is closed.

[0038] At this point, the preparation phase is over, and the position diagram of the buffer piston 240 and the impact piston 230 is as follows: Figure 1 shown.

[0039] Impact stage: When the impact command is given, the overflow detection circuit is closed and the inflation detection circuit 400 is opened to connect to the atmosphere. The purpose of closing the overflow detection circuit is to prevent the buffer oil from being discharged from the circuit, and the purpose of opening the inflation detection circuit 400 is to quickly discharge the high-pressure gas in the air cavity 272 and connect it to the atmosphere, ensuring that there is almost no back pressure when the impact piston 230 slides axially toward the air cavity 272 during the impact stroke; then the main valve core of the impact system high-speed switching valve is opened, and the impact return oil 100 is connected to the impact system return oil, so that the impact piston 230 accelerates to slide toward the air cavity 272. Since the air cavity 272 is connected to the atmosphere, the pressure required to push the impact piston 230 to move is very small, so the pressure loss of the impact system return oil is small and the energy loss is small; when the impact piston 230 moves to the end of the stroke, the impact stage ends and enters the buffer stage. At this time, the position diagram of the buffer piston 240 and the impact piston 230 is as shown in Figure 2 shown.

[0040] Buffering stage: the impact piston 230 moves to the root of the buffer piston 240, and drives the buffer piston 240 to extend in the direction away from the impact return oil 100. At this time, the flow rate of the oil in the return oil chamber 110 reaches a maximum value. During the extension of the buffer piston 240, due to the throttling and buffering effect of the damping hole 251, the greater the extension stroke of the buffer piston 240, the greater the pressure in the second side chamber, and the oil in the buffer piston 240 and the return oil chamber 110 is decelerated and buffered. Finally, before the buffer piston 240 reaches the end of the stroke, the oil in the buffer piston 240 and the return oil chamber 110 is decelerated to 0, and then begins to move in the retraction direction. After multiple layers of rebound, the buffer piston 240 finally stabilizes at the equilibrium position; at this point, the buffering stage ends, and the position diagram of the buffer piston 240 and the impact piston 230 moving to the extreme position is shown in FIG. Figure 3 shown.

[0041] In the oil return buffer device of the present invention, a dual piston of an impact piston 230 and a buffer piston 240 is used to realize acceleration and buffering action. The impact piston 230 is designed inside the buffer piston 240. In the impact stage, one end of the impact piston 230 is a high-speed and large-flow return oil, and the other end is an air cavity 272 connected to the atmosphere, so that the impact hydraulic system has almost no return oil back pressure in the acceleration stage. When the impact piston 230 moves to the end of the stroke, it enters the buffer stage, and the buffer piston 240 plays a deceleration and buffering role to realize the buffering and deceleration of the oil. Therefore, in the oil return buffer device of the present invention, through the cooperation of the impact piston 230 and the buffer piston 240, the entire impact buffering process has obvious impact stage and buffering stage. The return oil resistance in the impact stage is small (the air cavity 272 is connected to the atmosphere), and the instantaneous impact pressure in the impact stage decreases rapidly, which is not easy to cause damage to the cylinder assembly and the piston. In the buffer stage, the deceleration back pressure is obtained by relying on the oil pressure loss. The buffering effect is obvious and easy to control, which is suitable for the high-speed and large-flow return oil buffering field of the impact hydraulic system.

[0042] Alternatively, as Figure 1As shown, the oil return buffer device also includes a buffer piston rod 241 axially connected to the buffer piston 240, and the buffer piston rod 241 is located in the second side cavity so that the second side cavity forms a rod cavity 242. The cylinder assembly includes a hollow cylindrical cylinder 210, a first end cover 250 for closing the second end of the cylinder 210, and a first end cover cylinder body 252 axially connected to the first end cover 250 for accommodating the buffer piston rod 241. The first end of the cylinder 210 is connected to the oil return cavity 110. The buffer piston 240 is slidably disposed in the inner cylinder cavity of the cylinder 210, and the two are also in sealed contact via a sealing ring. The buffer piston rod 241 axially penetrates the rod cavity 242 and then extends into the first end cover cylinder body 252, and the buffer piston rod 241 and the first end cover cylinder body 252 are also in sealed contact via a sealing ring. In this optional solution, the cylinder 210 is cylindrical, and the first end face 211 and the second end face 212 of the cylinder are arranged on the two sides respectively. The cylinder 210 is fixed to the impact system return oil pipe or the high-speed switch valve group through the first end face 211 of the cylinder, and the impact system return oil is connected to the return oil chamber 110; a first stop 213 is arranged in the first end face 211 of the cylinder, and its function is to stop the buffer piston 240 when it retracts; multiple sealing rings are used to seal between the impact piston 230 and the buffer piston 240 to prevent the fluid on both sides of the impact piston 230 from leaking each other; the buffer piston rod 241 and the buffer piston 240 are integrated Type structure, the outer diameter of the buffer piston rod 241 is 0.2 to 0.6 times the outer diameter of the buffer piston 240, and the buffer piston 240 adopts a long piston design, which on the one hand ensures the impact stroke of the internal impact piston 230, and on the other hand enhances the guiding effect. When the impact piston 230 hits the buffer piston 240, the two can slide smoothly together to prevent jamming; the first end cover cylinder 252 and the first end cover 250 are an integrally formed structure, and the inner diameter of the first end cover cylinder 252 is slightly larger than the outer diameter of the buffer piston rod 241. The function of the first end cover cylinder 252 is to fully accommodate the buffer piston rod 241 when the buffer rod 240 is extended.

[0043] Alternatively, as Figure 1 As shown, the first end cap body 252 is hollow and cylindrical with both ends connected. The cylinder assembly also includes a third end cap 270 for sealing the free end of the first end cap body 252. The third end cap 270 is provided with an air hole 271 extending therethrough, which is connected to the inflation detection circuit 400. The buffer piston rod 241 is hollow and cylindrical with both ends connected. The ends of the buffer piston rod 241 are respectively connected to the air cavity 272 and the inner cylinder cavity of the first end cap body 252, so that the air cavity 272 is connected to the inner cylinder cavity of the buffer piston rod 241 and the inner cylinder cavity of the first end cap body 252 in sequence.

[0044] Alternatively, as Figure 1As shown, the inflation detection circuit 400 includes an air supply line connected to the air hole 271, and connected to the air supply line are a second needle valve 410, an air cavity pressure sensor 420, and an electric ball valve 430. In this optional solution, the second needle valve 410 is used to connect to an external high-pressure air source to inflate the air cavity 272, allowing the impact piston 230 to fully retract before the impact begins; the air cavity pressure sensor 420 is used to detect the pressure in the air cavity 272; and the electric ball valve 430 has a large diameter to minimize the throttling effect and its function is to quickly discharge the high-pressure gas in the air cavity 272 into the atmosphere.

[0045] Alternatively, as Figure 1 As shown, the first embodiment of the cylinder assembly further includes a second end cap 260 that is sleeved onto the outer circumference of the first end cap body 252 and located outside the first end cap 250. The second end cap 260 is recessed to define a buffer chamber 262 between the second end cap 260 and the first end cap 250. The second end cap 260 is further provided with a buffer oil port 261 extending therethrough and communicating with the buffer chamber 262. The buffer oil port 261 is connected to the oil filling detection circuit 300. The damping orifice 251 is a concentrically arranged, multi-circular annular hole formed on the first end cap 250, connecting the rod chamber 242 and the buffer chamber 262 via the multi-circular annular hole.

[0046] Alternatively, as Figure 4 As shown, the second embodiment of the cylinder assembly further includes an annular second end cap 260 that is sealingly fitted over the outer circumference of the cylinder 210. The second end cap 260 is recessed to define a buffer chamber 262 between the second end cap 260 and the cylinder 210. A buffer oil port 261 is also formed on the second end cap 260 and extends through the buffer chamber 262. The buffer oil port 261 is connected to the oil filling detection circuit 300. The damping holes 251 are a plurality of damping holes 251 arranged in a circle in the cylinder 210 in sequence along the axial direction. Each circle of damping holes 251 includes a plurality of damping holes 251 spaced apart in a circumferential direction, so that the rod chamber 242 and the buffer chamber 262 are connected through the damping holes 251 group.

[0047] Preferably, if Figure 4As shown, the diameter of the damping holes 251 in the multi-ring damping hole group 251 gradually decreases along the direction of the buffer piston 240's slippage. In this preferred embodiment, the damping holes 251 are located at the rod chamber 242 of the cylinder 210. The damping holes 251 open in a radial direction, and their diameter decreases as the buffer piston 240 extends. A second end cap 260 is located outside the damping holes 251 to collect high-pressure hydraulic oil throttled through the damping holes 251 from the rod chamber 242. A buffer oil port 261 is located outside the second end cap 260 for connection to the oil filling detection circuit 300. Unlike the beneficial effects of the first embodiment, during the buffering process, as the buffer piston 240 extends, the damping holes 251 are partially covered, and the flow area of ​​the hydraulic oil from the rod chamber 242 through the damping holes 251 to the buffer chamber 262 becomes increasingly smaller, resulting in a more pronounced throttling and buffering effect, and more reliable and effective buffering.

[0048] Alternatively, as Figure 1 As shown, the oil filling detection circuit 300 includes an oil pipeline connected to the buffer oil port 261, a ball valve 330 connected to the oil pipeline, and a buffer chamber pressure sensor 340. In this optional solution, the ball valve 330 is used to connect an external high-pressure oil source to fill the buffer chamber 262 and the rod chamber 242 with oil and maintain pressure; the buffer chamber pressure sensor 340 is used to detect the pressure in the buffer chamber 262.

[0049] Preferably, if Figure 1 As shown, the oil filling detection circuit 300 also includes a piston accumulator 320 connected to the oil pipeline. The piston accumulator 320 is provided with a separate air filling chamber and oil filling chamber. The air filling chamber is also connected to an external inert gas source through a first needle valve 310, and the oil filling chamber is connected to the buffer oil port 261. In this preferred embodiment, the air filling chamber of the piston accumulator 320 is connected to an external high-pressure gas source through the first needle valve 310 to adjust the pre-charge pressure. During operation, the damping orifice 251 and the piston accumulator 320 are connected in series to achieve deceleration and buffering effects. During the buffering stage, the buffer piston 240 extends, allowing the oil in the rod chamber 242 to pass through the damping orifice 251 and enter the buffer chamber 262 and the piston accumulator 320. After the dual throttling and buffering effects, the greater the extension stroke of the buffer piston 240, the higher the pressure in the rod chamber 242, and the more significant the buffering and deceleration effect. In the present invention, the entire impact buffering process has obvious impact stage and buffering stage. The return oil resistance in the impact stage is small, and the instantaneous impact pressure in the impact stage decreases rapidly, which is not easy to cause damage to the cylinder assembly and the piston. In the buffering stage, the deceleration and buffering of the buffer piston are achieved by throttling and buffering through the damping hole. The buffer piston is passively extended so that the oil in the rod chamber enters the buffer chamber and the piston accumulator in turn through the damping hole. After the double throttling and buffering effect, the greater the extension stroke of the buffer piston, the more significant the buffering deceleration effect. The buffering effect of this process is obvious and easy to control, and is suitable for the high-speed and large-flow return oil buffering field of the impact hydraulic system.

[0050] Alternatively, as Figure 1 As shown, the cylinder assembly further includes a piston cap 220 located in the first side chamber. The piston cap 220 is configured to axially abut the corresponding end of the buffer piston 240. The piston cap 220 partially extends into the oil return chamber 110, thereby abutting against the impact piston 230 to prevent the impact piston 230 from sliding out of the buffer piston 240. In this alternative embodiment, the outer diameter of the piston cap 220 is 6-12 mm smaller than that of the buffer piston 240, and the inner diameter of the piston cap 220 is 10-20 mm smaller than that of the impact piston 230. A second stop 221 is provided on the inner side of the piston cap 220 to abut against the impact piston 230 to limit its position.

[0051] Alternatively, as Figure 1 As shown, the overflow detection circuit includes an overflow line connected to the oil return chamber 110, and an oil return chamber pressure sensor 120, a solenoid valve 130, and a relief valve 140, which are sequentially connected to the overflow line. In this alternative solution, the oil return chamber pressure sensor 120 detects the pressure in the oil return chamber 110, the solenoid valve 130 implements logic control, and the relief valve 140 controls the oil return chamber pressure by overflowing.

[0052] The specific working process of the oil return buffer device of the present invention is as follows:

[0053] Preparation stage: The return oil buffer device is arranged at the return oil position of the high-speed switch valve of the impact system. The impact return oil 100 is connected to the return oil of the high-speed switch valve. At this time, the high-speed switch valve is not opened, the electromagnetic ball valve 130 is opened, and the pressure of the relief valve 140 is set to 10-20 bar;

[0054] The first needle valve 310 is opened to connect high-pressure nitrogen to the piston accumulator air chamber, and the needle valve is closed when the pressure reaches the target pressure. The ball valve 330 is opened to connect high-pressure oil to the buffer chamber 262 and the rod chamber 242, so that the buffer piston 240 retracts to the first stop 213. When the oil return chamber pressure sensor 120 detects that the pressure of the impact return oil remains at the set value, the buffer piston 240 is considered to have retracted into place. Subsequently, the ball valve 330 is closed after the pressure of the buffer chamber 262 is detected to remain at the target pressure.

[0055] Close the electric ball valve 430, open the second needle valve 410, connect high-pressure nitrogen to inflate the air chamber. The inflation pressure is 10-15 bar higher than the impact oil return pressure, causing the impact piston 230 to retract to the second stop 221. When the oil return chamber pressure sensor 120 detects that the pressure remains at the set value, it is considered that the impact piston 230 has retracted. Then, after detecting that the air chamber pressure remains at the target pressure, close the second needle valve 410.

[0056] At this point, the preparation phase is over, and the position diagram of the buffer piston 240 and the impact piston 230 is as follows: Figure 1 shown.

[0057] Impact phase: When the impact command is given, the commands to close the electromagnetic ball valve 130 and to open the electric ball valve 430 are given at the same time. The purpose of closing the electromagnetic ball valve 130 is to prevent the buffer oil from being discharged from the overflow valve 140, and the purpose of opening the electric ball valve 430 is to quickly discharge the high-pressure gas in the air cavity and connect it to the atmosphere, ensuring that there is almost no back pressure when the impact piston 230 slides axially toward the air cavity during the impact stroke. Then the main valve core of the high-speed switching valve of the impact system is opened, and the impact return oil is connected to the impact system return oil, so that the impact piston 230 accelerates to slide toward the air cavity. Since the air cavity is connected to the atmosphere, the pressure required to push the impact piston 230 to move is very small, so the pressure loss of the impact system return oil is small, and the energy loss is small. When the impact piston 230 moves to the end of the stroke, the impact phase ends and enters the buffer phase. At this time, the position diagram of the buffer piston 240 and the impact piston 230 is as shown in the figure. Figure 2 shown.

[0058] Buffering stage: the impact piston 230 moves to the root of the buffer piston rod 241, and drives the buffer piston 240 to extend in the direction away from the impact return oil 100. At this time, the flow rate of the oil in the return oil chamber 110 reaches the maximum value. During the extension of the buffer piston 240, due to the dual throttling and buffering effects of the damping hole 251 and the piston accumulator 320, the greater the extension stroke of the buffer piston 240, the greater the pressure in the rod chamber 242, and the oil in the buffer piston 240 and the return oil chamber 110 is decelerated and buffered. Finally, before the buffer piston 240 reaches the end of the stroke, the oil in the buffer piston 240 and the return oil chamber 110 is decelerated to 0, and then begins to move in the retraction direction. After multiple layers of rebound, the buffer piston 240 finally stabilizes at the equilibrium position; at this point, the buffering stage ends. The schematic diagram of the position of the buffer piston 240 and the impact piston 230 moving to the extreme position is shown in the figure below. Figure 3 shown.

[0059] A preferred embodiment of the present invention also provides an impact test system, in which the return oil pipe or high-speed switching valve group is connected to the return oil buffer device as described above. Thus, in the impact test system of the present invention, the entire impact buffering process has obvious impact stage and buffering stage. The return oil resistance in the impact stage is small, and the instantaneous impact pressure in the impact stage decreases rapidly, which is not easy to cause damage to the cylinder assembly and the piston. In the buffering stage, the deceleration back pressure is obtained by relying on the oil pressure loss. The buffering effect is obvious and easy to control, and is suitable for the high-speed and large-flow return oil buffering field of the impact hydraulic system.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An oil return buffer device, characterized in that: include: Cylinder assembly, buffer piston (240), impact piston (230), overflow detection circuit, oil filling detection circuit (300) and air filling detection circuit (400); The cylinder assembly is in the shape of a hollow cylinder for connecting to an impact test system, and has a first inner cylinder cavity arranged along the axial direction, and a buffer cavity (262) connected to the first inner cylinder cavity through a damping hole (251), and the buffer cavity (262) is connected to an oil filling detection circuit (300) so as to perform oil filling and pressure detection on the buffer cavity (262) through the oil filling detection circuit (300); The buffer piston (240) is slidably disposed in the first inner cylinder cavity to separate the first inner cylinder cavity into a first side cavity and a second side cavity located on both sides thereof and not connected, and the second side cavity is connected to the buffer cavity (262) through the damping hole (251); The buffer piston (240) is hollow and cylindrical, and has a second inner cylinder cavity arranged along the axial direction. The impact piston (230) is slidably arranged in the second inner cylinder cavity to separate the second inner cylinder cavity into an oil return cavity (110) and an air cavity (272) located on both sides thereof and not connected. The oil return cavity (110) is connected to the first side cavity and is used to communicate with the impact return oil (100) of the impact test system. The oil return cavity (110) is also connected to an overflow detection circuit to allow the lubricating oil in the oil return cavity (110) to overflow and to detect pressure. The air cavity (272) is connected to an air charging detection circuit (400) to charge the air cavity (272) through the air charging detection circuit (400), detect pressure, and discharge the gas in the air cavity (272) to the atmosphere. The oil return buffer device further comprises a buffer piston rod (241) axially connected to the buffer piston (240), the buffer piston rod (241) being located in the second side cavity so that the second side cavity forms a rod cavity (242); the cylinder assembly comprises a hollow cylindrical cylinder (210), a first end cover (250) for sealing the second end of the cylinder (210), and a first end cover cylinder body (252) axially connected to the first end cover (250) for accommodating the buffer piston rod (241), the first end of the cylinder (210) being communicated with the oil return cavity (110); the buffer piston (240) being slidably disposed in the inner cylinder cavity of the cylinder (210), and the two are in sealed contact via a sealing ring; the buffer piston rod (241) axially penetrates the rod cavity (242) and then extends into the first end cover cylinder body (252), and the buffer piston rod (241) and the first end cover cylinder body (252) are in sealed contact via a sealing ring; The buffer piston rod (241) is in the shape of a hollow cylinder with two ends connected, and the two ends of the buffer piston rod (241) are respectively connected to the air cavity (272) and the inner cylinder cavity of the first end cover cylinder (252), so that the air cavity (272) is connected to the inner cylinder cavity of the buffer piston rod (241) and the inner cylinder cavity of the first end cover cylinder (252) in sequence.

2. The oil return buffer device according to claim 1, characterized in that: The first end cover cylinder (252) is in the shape of a hollow cylinder with two ends connected; The cylinder assembly further comprises a third end cover (270) for sealing the free end of the first end cover cylinder (252). The third end cover (270) is provided with an air hole (271) extending therethrough, and the air hole (271) is connected to the inflation detection circuit (400).

3. The oil return buffer device according to claim 2, characterized in that: The inflation detection circuit (400) comprises an air delivery pipeline communicating with the air hole (271), and a second needle valve (410), an air cavity pressure sensor (420), and an electric ball valve (430) connected to the air delivery pipeline.

4. The oil return buffer device according to claim 1, characterized in that: The cylinder assembly further includes a second end cover (260) which is sleeved on the outer circle of the first end cover cylinder (252) and is located outside the first end cover (250). The second end cover (260) is concavely arranged to enclose a buffer cavity (262) between the second end cover (260) and the first end cover (250). The second end cover (260) is also provided with a buffer oil port (261) which is arranged through and communicates with the buffer cavity (262). The buffer oil port (261) is connected to the oil filling detection circuit (300). The damping hole (251) is a concentric multi-circle annular hole opened on the first end cover (250), so as to connect the rod cavity (242) and the buffer cavity (262) through the multi-circle annular hole.

5. The oil return buffer device according to claim 1, characterized in that: The cylinder assembly further includes a second end cover (260) that is annular and sealingly sleeved on the outer circle of the cylinder (210); the second end cover (260) is concavely arranged to enclose a buffer cavity (262) between the second end cover (260) and the cylinder (210); a buffer oil port (261) is also provided on the second end cover (260) that is arranged through and communicates with the buffer cavity (262); the buffer oil port (261) is connected to the oil filling detection circuit (300); The damping holes (251) are a group of multiple damping holes (251) sequentially opened on the cylinder (210) along the axial direction, and each group of damping holes (251) includes multiple damping holes (251) sequentially spaced along the circumferential direction, so that the rod cavity (242) and the buffer cavity (262) are connected through the damping holes (251) group.

6. The oil return buffer device according to claim 5, characterized in that: The apertures of the damping holes (251) of the multi-ring damping hole (251) group gradually decrease along the buffering sliding direction of the buffer piston (240).

7. The oil return buffer device according to any one of claims 4 or 5, characterized in that: The oil filling detection circuit (300) comprises an oil delivery pipeline connected to the buffer oil port (261), and a ball valve (330) and a buffer chamber pressure sensor (340) connected to the oil delivery pipeline.

8. The oil return buffer device according to claim 7, characterized in that: The oil filling detection circuit (300) further includes a piston accumulator (320) connected to the oil delivery pipeline. The piston accumulator (320) is provided with a gas filling chamber and an oil filling chamber separated from each other. The gas filling chamber is also connected to an external inert gas source via a first needle valve (310), and the oil filling chamber is connected to the buffer oil port (261).

9. The oil return buffer device according to claim 1, characterized in that: The cylinder assembly further includes a piston cover (220) located in the first side cavity. The piston cover (220) is used to abut against the corresponding end of the buffer piston (240) along the axial direction, and the piston cover (220) partially extends into the oil return cavity (110) to abut against the impact piston (230) to prevent the impact piston (230) from sliding out of the buffer piston (240).

10. The oil return buffer device according to claim 1, characterized in that: The overflow detection circuit comprises an overflow pipeline connected to the oil return chamber (110), and an oil return chamber pressure sensor (120), an electromagnetic ball valve (130), and an overflow valve (140) connected in sequence to the overflow pipeline.

11. An impact test system, characterized in that: The oil return pipe or the high-speed switch valve group is connected to the oil return buffer device as described in any one of claims 1-10.

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